Transmission won't shift?

The automatic transmission in my 1994 Ford Ranger won't shift. I can put in gear but it won't engage. I have changed the vacuum modulator. As well as changed the fluid and filter making sure I was at the correct level. Any idea what could be going on? The engine is 3.0L there are approximately 180k miles on the original transmission. I don't know enough to really troubleshoot what's going on. Would like to fix it myself or at least try before taking it to the shop. Any help is appreciated -thanks

Its toast. Generally you go somewhere and have a rebuilt one put in and call it a day.

Replace the governor.

This also has a kickdown cable that is in front of the linkage. If that's broken then it won't shift. Also a governor inside the extension housing on the output shaft which also has something to do with no upshift. If that is stuck then something inside internally is breaking up and causing that valve to stick. More help find local shop at ATRA.COM

If the vehicle does not move when the tranny is in gear it's slipping and the transmission needs rebuilding.

It's possible the linkage between the shifter stick and the transmission is dislodged or out of alignment, so that the shifter goes into the right position but that isn't communicated to the transmission. It's certainly worth checking that first before indulging in anything expensive.

Trans is bad, replace.

God created s**t, Ford put it on wheels, good luck with that