Hello,
I have a FS202Pro.  I downloaded and installed a lot of add-on airplanes and gauges.  During installation I had to overwrite same files because I installed gauges for specific aircrafts.  My default airplane's gauge is working fine; however, all the add-on airplane gauge is not working.  Particularly altitude indicator.  When I bank aircraft to left aritifical horizon moves to right. When I tried to bank right AH moves to left.  It is really annonying.  How to remedy this problem?  Also how do you relaease tailhook from fighter jets?
This problem only applies to download aircrafts not default aircrafts from FS202pro. 
I look forward solution to my problems. 
Thanks and have a nice day.

Yeah, that's a big no no.

NEVER extract .gau files directly into your FS2002\Gauges folder.  ALWAYS extract them to a temporary location first, then you can cut & paste them into the Gauges folder.  If you asked to overwrite say no.  (There are a very few exceptions to this rule but if you do not know exactly what you are doing just say no.)

You can get the default MS gauges back.

On CD1 open the file named FS2002.cab with winzip or winrar or something like that.  Within FS2002.cab extract all files in the \Game\gauges folder.  Cut & paste all of the .gau files back into your (HD) FS2002\Gauges folder, saying yes to overwrite your existing bad files.

The tailhook key is not not assigned by default.  To add a key command go into the settings menu and scroll down.  You will see "Tail hook up/down" is unassigned.  Assign an unused key to it.  You only need one key because it's a toggle.  I use Shift-T, I guess T was already in use.  The tailhook won't work unless the aircraft has one built into the model (although you should see a "Tailhook extending" notice) and even then it's just a visual effect.  You need one of the tailhook addon packages to add functionality - like the carrier ops package from Rob (I'm probably spelling this wrong) Berendecht.