What is wrong with my Mazda b3000 won't shift into gear?

I had the same problem and took it to a mechanic. From what I could tell it was a simple part replacement, a small part. I can not remember the exact name of it however, but i am sure it was a berring. It was a cheap part. The labour cost me $300 dollars though. Be sure to check your clutch fluid- if it is too low or has droped too low then you added more (air in lines) you wont get any gears either.