By accident when i reisntalled XP it overwitten all my documents and settings and lost a lot of important files in mydocuments folder!

I went to install several undeleters, which all finds the deleted files. Problem: When i restore the files of all formats, the associated programs dont recognise them. I.e. word documents come up in gibberish and access files (very important ones (and all other ones) ) doesn't open - is there anyway to solve my problem or to decode these files to make them recognisable again?