Help retrieving deleted files

I really made a mess of things, and I'm not sure where to start. I stupidly downloaded Mackeeper and ran it. After seeing the negative posts, I uninstalled it and emptied my trash. Now, I can't access documents on my computer. When I try to open up a document, a message says it is being used by another user. (I'm not sure what other programs it affected.) I don't know what to do. Can these files be retrieved from anywhere, or am I totally screwed? I haven't done a recent backup, and I know I will lose certain important docs.

Any help would be greatly appreciated! Thanks.

Try rebooting the machine first of all.

And what types of documents - all of them, some, only a particular file type?

Do you have multiple user accounts on the machine?

Yes, I restarted the computer and the docs are still unavailable. When I click on them, a message poops up asking from which program to convert. These were word docs, but when I click "Microsoft Word" it says that 'The XML file cannot be opened because there are problems with the contents.
Details:
Incorrect document syntax
Location: 1

All of these worked prior to using MacKeeper?

Have no answer for you - don't use any MS products in OS X myself.

One solution I found while searching suggests opening them in TextEdit or LibreOffice - then copy/paste the text back into a new word doc. This may not be an acceptable solution if we're talking hundreds of files.

You might want to provide what version Office you're using.

Okay, thanks so much for your help. Appreciate the effort.