Why can't i change gears on my manual transmission car?

I have a 2004 ford ranger 2.3 4 cylinder with manual transmission. I can turn it on but I'm not able to shift gears. Is it the clutch master cylinder, slave cylinder or transmission?

Whatever… If you're not a savvy auto mechanic person, you'll have to have it towed

Those are all suspect. Start with the clutch cylinder.

Common one is the slave. But the transmission would need to come out to replace it.Find local shop at ATRA.COM for more help

Any of the above.

This is why mechanics earn the big bucks. They put vehicles up on hoists etc and actually look to see what's happening underneath.

It's likely a problem with the hydraulic clutch system. Does the clutch pedal feel spongy or stick to the floor? Have you even checked the fluid level in the clutch master cylinder reservoir yet?
You need a mechanic.

Might need a new clutch; see a Ford mechanic. Get more than one estimate.

The major fix needed is the slave cylinder more then likely.
Check the fluid level on the system, if it is low, top it off and bleed the system.
If it is full then the problem is the master cylinder.
Here is the problem:
The slave cylinder is internal the bell housing. So the engine transmission must be separated to be replaced. Also one reason these assemblies start leaking is that they are at the limits of wear on the clutch plate. This means that all the labor (about six hours labor) is paid for that will be needed to replace the clutch, pressure plate and to resurface the fly wheel. The logical path is to get all of these done at the same time so you don't have to pay for the labor bill twice when once will do.

Probably.
Crystal ball broken!