I lost the Amazon mp3 downloader. Where can go to get it back?
It will help those who troubleshoot for a "living" if you explain exactly which mod/froyo upgrade you used. It is possible that the file you need is there, but perhaps needs to be renamed if it was .bak'd rather than being omitted. Take a peek in the system/app folder for the file, if you know exactly which one it is. A few of the newer roms are coming with scripting features that might allow you to simply restore it. Again, which rom and how you got to where you are would help troubleshoot.
One method to find the file is to pull it from an earlier downloaded froyo update file (not nandroid style backup) that you know has it. You can extract that zip file on your pc with a program like 7 zip, and all of the programs will be there. Depending on your skill level there are ways to get this file back onto your phone.