My .CRM file is missing part of the audio after I accidentally linked it to a .MXF proxy file

Do you have all audio in the CRM file if you play it in a media player such as VLC or PotPlayer?

I don´t know if any of them can playback CRM files, but the important part is to playback the file outside any Adobe app to hear if there is any audio in the CRM file to begin with.

If you can hear audio in the whole file, hold down the Shift key at the same time you launch Premiere Pro. This will give you the Reset options dialog. Check the Clear media cache files and click Continue. This will delete the media cache database that probably is corrupted.

Plus: It will give you the audio back.

Minus: All your files will have to be re-conformed and that will take some time for large projects.

While the re-conforming is in progress, avoid to do anything with the project until it´s done. Starting to edit/playback files while they are conforming can cause issues like you have, iow that portions of the audio goes silent.

Does anyone have an idea of how to get this missing part back?

By @GGTVVIDEO

Never easy to troubleshoot premiere problems from a distance so please tell us your system specs: OS version, Premiere version, amount of RAM, Hardware specs, etc.

Wondering if the original full rez file (.mxf) file has been corrupted in which case not sure if there's a solution.  You might run a disk utility (like diskfirstaid and diskwarrior on the mac) on the hard drive to see if that helps.  Also, maybe try and transcode the file to a "mezzanine format" like prores...

And although it may be too late, always important that you have your source media backed up at least a couple of times...  Every hard drive will fail.  It's a question of when not if...