What version of the Movie Edit Pro do you have?

I am not sure what might cause that, I was initially thinking maybe a track was locked, but I am still able to add to locked tracks, but unable to move the content when lock? (Movie Edit Pro MX Premium)

What is format of the content file you are attempting to add?

You stated you can import the content to a new project, is that content the same as the content that will not load in the original project?

I tryied importing different and same files files.

I also tryied importing mp3, jpg, vts extensing and it keeps doing the same.

I'm using movie edit pro 17.

I am not sure, I have never seen this behavior before. I would suggest uninstalling and reinstalling the software.

Hi

Before you try reinstalling the software try this fix which often works:-

Using Windows Explorer search for the file videodeluxe.ini or movieedit.ini (depending on which version of MEP you have) the file may be hidden so you have to search hidden folders.

You may find several of them - the one you want will be the largest one with a file size in the range 12- 21kb.

Delete the file.  Note any customised setting you have set will be lost.

Start MEP again and try importing the videos as before.

If this fails then do John's suggestion - however before reinstalling run the Magix cleanup tool available here http://support2.magix.com/customer/en/download/tools

HTH

John