I have a 2002 Mazda Miata 5 speed manual transmission and the shifter is stuck in the reverse position. Clutch had just been replaced.

99 00 01 02 03 FORD F150 MANUAL TRANSMISSION 5 SPEED MAZDA-TOYO KOGYO 4X2 8 CYL

will it shift if you double clutch ?

might be a shift linkage adjustment
internal shift fork has broken a scroll pin

clutch fork movement ok ?

It appears this is a 5 speed manual transmission. There may be shift linkage problems between the shift lever and transmission. also bushings. I strongly recommend a repair manual specificly for this transmission. possibly filespeep.com or manualslib.com
How is the clutch and throwout bearing?

http://www.techguys.ca/howto/transmission_fluid.html

In addition to this site I have heard that you can remove the shifter boot and plate for easier access to the fill hole.

Did you check you gear oil?

Reverse synchronizer could be defective. The clutch could need adjustment but this does not seem likely as it is only doing this in reverse.

The one item I would suspect is the through-out-bearing not completely disengaging the pressure plate from the fly wheel. If the vehicle is in neutral and you slowly depress the clutch and release it do hear a singing or whining sound? Since you cannot adjust the clutch any more the through-out-bearing is the component which moves the pressure plate from the fly wheel to stop the power from the engine to the transmission. It is difficult to shift when the engine is on because the fly wheel is still engaged and powering your transmission.

you will need to take the trans out and maybe get it back by looking through the shifer hole...maybe. I would take it to mazda ( or a shop that works on a lot of Miatas) and hope they can do it easily. . The drain is on the bottom, how did that get confused?

Yes you most likely have a bad throw out bearing. If you replace the bearing you would do yourself a favor and replace the clutch and pressure plate while you are there.

You will have to remove the center console and then the shifter asm. look down inside where the shifter goes and you will see 3 selectors one will be out of position. You will need to pop it back inline with the other 2. After that look at the bottom of the shifter ther should be a bushing on the very end, if it is not there you will need to get one from your dealer, they are like 8 dollars and then you just pop it on and reasemble in reverse order and you should not have any more trouble.

sounds like shifter fork inside transmission has broken, literally snapped in two.