When you say “follow me extensions”, are you talking about internal extensions or external destinations? If it’s external destinations that aren’t working then it may be an issue of some kind with a provider.
If I were you I’d consider doing this. First, grab one of the free online e-books such as “Elastix Without Tears” or “PBX in a Flash” without tears - most of what’s in those will be applicable to your installation, and you can skip the parts that aren’t. If your employer will buy it, there’s a FreePBX book by Alex Robar (sold by Packt Publishing) that’s supposed to be pretty good, if a little pricey. Use your favorite search engine to find those. Use those to learn about the system you’ve inherited
If you just can’t get things working again, and you’re getting desperate, then get the ScreenGrab! extension for Firefox and take a complete page screenshot of every page in your existing FreePBX installation (every extension, every follow-me, every inbound and outbound route, every trunk, every IVR, etc. - it may take a while but you want a screenshot of everthing. If there are any text fields that have contents that overflow the screen (or that you don’t want to have to re-type manually), cut and paste the entire contents of those fields to a separate text file. Also use the Bulk Extensions and Bulk DIDs modules in FreePBX to make a backup of your extensions and inbound routes, and then do an entire system backup (making especially sure you have a backup of the entire /etc and /var directory trees). Back all of this up onto a totally different computer.
Then using the instructions in one of the aforementioned free E-Books, install either Elastix or PBX in a Flash. I personally prefer Elastix because in past experience I’ve had fewer issues with it, but it’s up to you. The idea here is to get back to a known, pristine state. Do take note of the fact that the installer will completely wipe and reformat the system’s hard drive INCLUDING all connected drives (even thumb drives, etc) so don’t leave any drives connected that have something you want to keep on them.
Once you have installed the new software and upgraded FreePBX using the module administration tool, you can use the Bulk Extensions and Bulk DIDs modules to restore your extensions and inbound routes, and use your screenshots and the text file you made to restore everything else. Once you do that you will be in a position where if things still don’t work, you can go to the forums for whichever package you installed and ask for help.
I realize there’s also a backup and restore module in FreePBX and while you could try to use that, chances are the software package you install is going to install a newer version of FreePBX, and for that reason the restore might fail. You can try using that also, but if it doesn’t work you’d still have your screenshots and text file to help you get your extensions, trunks, routes, etc. reconfigured.
I wouldn’t rush right out and do this (except for getting the book(s)) because for one thing, someone else may see this and may be able to tell you how to fix your specific issue without doing all this. But one thing I know is that when you inherit someone else’s system, you also inherit their customizations, and if you don’t know what those are they can cause things to break. If you start out with a pristine system then you don’t need to worry about that as much, and if none of the users complain that something that used to work doesn’t anymore, than any such customizations may be no longer necessary. I hope you don’t have to do all this, but sometimes it’s better to just start over then spend a week or two trying to figure out why something just stopped working, when you could have had a new and upgraded system installed and configured in that amount of time.