Video files won't play at all - WMP/AVI

OK, this isn't my computer - I'm posting this for a friend b/c she does not have internet. So bear with me, I'm going off of what she told me is going on.

She downloaded some videos off of hers and her boyfriends phones. The played just fine at first, but she could not open them in Windows Movie Maker. She used a converter (not sure which) that she has used before (without a problem) to convert the files to AVI (I don't know what they were before).

Her computer was running slow (not sure if it was related or not) so she did a disk cleanup and a defrag. Since then, she cannot open -any- video files on her computer.

I told her to do basic troubleshooting. First thing, in case a file got moved, I told her to do a system restore. She tried it, got an error message. Tried again, got another error message. (I just sent her a message asking for an error number, please standby)

She is currently running an antivirus scan (Panda Antivirus Pro 2012). Her operating system is Vista, 465GB hardrive w/ 351GB free, 3GB RAM.

I am fairly computer literate, but this has me stumped. AKA - you can talk technical, if I don't get it I'll ask. I'll dumb it down for her.

 

OK, the system restore error was:

"System restore did not complete successfully. Your computer system files and settings were not changed."
Details:
An unspecified error occurred during system restore.


So far, at 31% 3 spyware infected files have been detected and resolved.

 

bump - please?? She's really upset about this, just wants her videos back...

 

Didn't anyone told you not to bump here because it makes it worse? There was a link in registration e-mail.

I hope I don't break any rules posting this.

I suppose the file was 3gp? Did the converted files work(newly converted)?
Did something happened with this video files?
What about other video formats? No video file works? What about audio files(if she has some)?
Are the codecs OK? Maybe codecs removal and re-installation would help?
How big are the files? Can you try open them on your machine? This would tell us if the files are broken or not.
What does it say when she tries to open a video file?

 

I'm sorry, I didn't know. I saw other people doing it, and no-one said anything, so....

Anyway, won't happen again.

3GP - I'll ask what they were before conversion.
Yes, they did work before and after they were converted. (Just not after disk cleanup and defrag)
Its not just AVI files that aren't working. No video file on her computer will work. As far as audio, she didn't tell me that they didn't, and she listens to her music all the time, so I'm going to say they work. I'll make sure though.
I'll tell her to try uninstalling and reinstalling the codecs.
I'll have her try to send me one to see if it works.
When she tries to open any video file, it says that windows cannot find an appropriate program to open it with. (Not verbatim) The icons are blank pages with the page curled, and four tiny images in the center of the page.

 

Don't worry about it, I'm no mod or anything. Just advice for future

I guess 3GP they were before conversion.

It seems that the problem is simpler than I thought...
From thread title I suppose that she uses WMP to watch videos.
What does she use for audio then? I'd guess not WMP? but to the point...
Tell her to open WMP(or whatever she uses to open video files) and use the program open command(you know, File|Open or something).
It looks like just file associations are gone. If I'm right then after restoring those everything will be fine.