Andre,
Others may have ideas about how to proceed, but here is my suggestion:
- Install the latest version of WEC Starter Package separate from the old directories
- Create a directory in fileadmin called something like fileadmin/old/ and copy your old fileadmin and uploads directories into the fileadmin/old/ directory. While you are at it, you can copy typo3temp and typo3conf into the same fileadmin/old/ directory.
fileadmin - My guess is that there are lots of files in fileadmin that you will need and you may even want to copy some of the directories to your main fileadmin.
uploads - There might be some files in uploads that you will need to sift through. They may have funny names, but this may be the only location for files that were not first uploaded to fileadmin.
typo3conf - I do not think there is much in here that won't get redone when you install extensions. You can use it to remind you which extension were installed. I suppose that there may be a few other things in there you might want to peek at at some point.
typo3temp - There is probably not anything in here that you need.
Unfortunately, the way content management systems work, the database is the key to most everything. So the hosting company really did damage by losing it. Backups are expensive for hosting companies, so sometimes they don't do them well and we lose stuff. A few years ago I was hosted at a low cost hosting company and learned that they did not make backups at all -- ouch. Well, we wish you the best and we feel your pain. It is just going to take a lot of time to recover from this.
In Christ,
Mark