It sounds like your predecessor tried to remove the phone number field and failed to do so correctly. You have a couple choices at this point as to how to proceed. No matter what you path you choose you should make a backup first.
1. Add the field back in.
2. Finish removing it.
3. restore to the distribution version.
With out seriously digging into your files we would have no way of knowing how much your predecessor changed the code. I personally recommend option 3. as it is the least technical. If you want to do 1. or 2. I recommend that you find a good guide that shows step by step how to add a field. The basics of that guide would allow you to do either.
