can not shift into any gear-standard transmission

The clutch is not properly "breaking" the drive between the engine and transmission when the pedal is depressed. make sure there isn't a floor mat sticking under the pedal. The clutch in your car is operated hydraulically check the fluid level in the reservoir, if it is low top it up bleed the clutch hydraulics and investigate the source of the leak.

i had this problem for awhile on my 89 Turbo. I have since replaced the master and slave clutch cyl and bled the system. I thought it was fixed but after a few weeks my problem is back. Occasionally it will work and you just never know when it will not get into the gear the next time you start it. I am boggled by this problem. I am ready to open up the tranny but hesistant. I would like to narrow the problem to the source itself before taking the entire thing apart.

a bad pressure plate will also cause this..it did it in my truck as well

I had the same problem with my 944T - could not shift with the engine running.I tried all of the above including flushing and changing the transmission fluid. I ended up replacing the clutch which solved the problem. Unfortunately, it is an expensive repair - $575 for the clutch kit (on the internet) plus another $100 for misc. parts. Labor can run 14 to 20 hours @ $100 +/-/hour. Be aware that some Porsche Repair Specialist will not use the parts that you purchased since they mitake $'s on the parts. Also, while you are at it, install a short shift kit - definitely worth it.