From your backup files, of course.  You do backup your data, don't you?

Now having stepped down from the soapbox, it you have not shut doen the computer since you deleted the files, there are commercial progams desgined to retrieve deleted files.  But I am sad to tell you, that data is gone forever.

There is no easy way to do that; it requires a professional data retriever (in my Yellow Pages, they are under Data Recovery as well as under several Computer Headings).  And even then there is no guarantee that the files have not been overwritten which makes it even more difficult, though not impossible.  What type of files were they?  If data files then, you probably will have to make do without them unless you spend some money.  If program files of one sort or another, you can reinstall the program.  If system files, then run SFC /SCANNOW (from the command prompt, not Start|Run) with your XP CD in the drive and any missing files will be replaced.

You could also try System Restore , depending of what file types they were.

Thanks for all your help; got it solved.