help locating old databases/or help adding existing content to a new db

Guys,
Hope someone can help. I used to be more active online and build a few sites on wordpress for myself and friends. The problem was that I was involved in a completely different project in the jungle and lost quite a bit of touch with those.

Im getting back on track now and my server helped me get my info back. yet it seems that on two of the sites (wp) there are database problems once one logs into them. Via FTP, I can see the info regarding the content of the sites is there but it doesnt seem to work if i just try and load the domain.

So can one find out where a db is if one has the name, the user and the passwords for this databases?
If the databases are gone, but the info is available on the FTP, how can i load my existing website into a new database?

Anyway hope my questions are clear, you are probably all pros and this may come off as a weird question but any help would be greatly appreciated.

Thanks
Mauricio