Rescue Your Video Tapes 4 (RYVT) is an old version and is not Windows 10 compatible.
You can try updating the USB devices driver with this version here, however you may find that Windows 10 will not allow these to be installed.
It is highly likely that Windows was recently updated to Windows 10 version 1703 (Creators edition) and this has rendered RYVT inoperable due to the changes installed by the Windows update.
. . . . I have uninstalled the programme. I have down loaded it again but now it is not taking the serial number. . . . .
This could be because of item 2 or the version downloaded is the current version in which case the serial number for version 4 will not work, you have to purchase a new licence/serial number.
The only solution is to purchase/upgrade RYVT to the latest version which is Windows 10 compatible.