I took my car to a mechanic and he said my 700R4 tranny is stuck in first gear thats why it's always reaching 5500RPM on 40mph, but is there any way to make it unstuck?

why didn't you ask the mechanic when he told you that?

Tell us more about when this problem first occured.

Is it a new install? Did this happen all of a sudden or has it been getting gradually worse? Was it after someone worked on it? After you added a new shifter? After you put in a shift kit? After a carb replacement? When you were just driving around town and heard a major "clunk" or something? How many miles on it since it was last worked on? etc.

The 1st 3 places I'd look are:
-under the car to see if the shifter linkage is working properly
-Pull the dipstick to see if the fluid level, and the fluid's condition are all normal
-see if the TV cable is adjusted properly.

If all that checks out fine, the other thing I might investigate is the transmission's governor. Do the spring and flyweights all look normal?

If all that fails, drive it slowly to a professional and have them look into it more deeply.

Hope it helps.
Mike

With all due respect. Don't try to fix this problem yourself, you are obviously way over your head. Take it to a good trans shop for diagnosis and a repair estimate.

all those 2 things are not working, the shifter is real loose

under the car to see if the shifter linkage is working properly

-see if the TV cable is adjusted properly.