Have you tried reinstalling?
There is rather common 'Elevated Privilege' issue with Sound Forge 10 which typically occurs on some PCs after a Win 10 update... however I do not recall the '0xc000012f error as a symptom of that. I am not sure about SF-10 on Win 11 PCs.

You might consider upgrading to the current version (SF-17). Your SF 10 activation serial can be used for the upgrade discount on SF Audio Studio 17 or SF Pro 17.

btw, welcome to the Magix Sound Forge users community @Neelam-Panditpautra.

How much it cost for the latest version?

@Neelam-Panditpautra Try resetting the program settings. Hold CTRL and SHIFT and double click on the Sound Forge program icon to start the program. Keep holding CTRL and SHIFT until a small window appears that will ask you if you want to reset the program settings.

How much it cost for the latest version?

Hi @Neelam-Panditpautra, the current upgrade price for the perpetual version (you own it forever) looks to be $39.99 (usd). SFAS-17 is currently on sale for first-time buyers for $49.99. So you would save $20 off the regular retail price of $59.99 usd.
https://www.magix.com/us/music-editing/sound-forge/sound-forge-audio-studio.
If you have questions about the price, email Magix customer service: sales@magix.net or infoservice@magix.net.

Otherwise, I think the 0xc000012f error code is a (missing file) error, so I am not sure a reset will resolve the problem, you can certainly try it though.
btw, Legacy versions of SF did not have the 'Reset/Clear Cache' command in the 'File' menu, so it must be down alternately. Hold down the 'Ctrl+Shift' keys whilst launching SF opens the reset dialog as @SP. stated. This also works for current versions when SF cannot be launched to access the File menu.

Thank you so much for giving all this info.

I had to uninstall the program and reinstall it. However, once reinstalling my serial number is not working. Would you know why?

@Neelam-Panditpautra We need to no the exact error message.

Initial error message was Error : 0xc000012f Then as per suggestion tried to re install but now it doesn't accept my serial number

@Neelam-Panditpautra

The Microsoft Support page on that specific error code is here. It points to the problem being because a part of your Windows installation is missing or damaged. You must repair this before your software will function properly!

With regard to the serial number problem, what error message does that produce? It is entirely possible that the missing files indicated by your stated error code could also impact this problem but if not, it will produce a different error message I believe.

HTH

Jeff
Forum Moderator

@Neelam-Panditpautra If you Windows seems damaged please check if all pending Windows updates were successfully installed. If not, please install them.

Thank you.

There in no error message after writing serial no., but it goes back to same page and asking serial no. again.

@Neelam-Panditpautra I think you are doing something wrong. You need to enter the serial number into the registration window during program start-up. It will show a red X if the serial number is invalid or error -14 or -24.

Can you please upload a screenshot of where you are trying to enter the serial number? Please make sure to make your serial number unreadable before uploading.

Did you download the installer from your customer account at Magix.com? Or is this an old Sony installer? The old Sony installer might no longer work. Sony turned all registration servers off.

All customer accounts were transferred from Sony to Magix. You need to download the installer from Magix.

@Neelam-Panditpautra Can you download the installer from here?

https://www.magix.com/int/support/my-service-center/product-downloads/

I recall that is one of the symptoms of the SF-10 'Elevated Privilege' issue. Try opening SF-10 as an administrator.
Right-click the Sound Forge 10 <.exe> launcher (or shortcut), choose 'Properties' and select the 'Compatibility' tab. Check-mark "Run this program as an Administrator" .

Tried : https://www.magix.com/int/support/my-service-center/product-downloads/

but says

'Invalid serial number

Please enter a valid serial number.'

"Try opening SF-10 as an administrator"

How to do this ? From where to open SF 10?

Serialno. is not working

A shortcut is usually put on the desktop when SF is installed. Otherwise, a shortcut can be created from the main launch <.exe> file (similar to <Forge100.exe> in the
"C:\Program Files (x86)\Sony\Sound Forge..." folder. I do not have SFAS-10 so I do not know the exact folder/file naming, but it would be similar to what I have (SF Pro-10).
SFAS-10 can also be downloaded from the SCS (Sony) archives. However the activation serial you have may be invalid or wrong so reinstalling with the last build (252 I think) may not help. I am also not sure if the Sony versions' serial code and the users email address are paired.. as it is with the Magix versions.