My 2002 jeep grand cherokee won`t change out of first gear I can only drive under 25 mph?

Check fuses.
then scan it.
the scan tool will in fact tell you what the trans is stuck
The PCM shifts the gears, so if it cant, it complains big time.
those are called DTC errors.
all shops in town can scan, or you can buy one and DIY.
on all modern cars. 96+

at 25mph 2nd should happen.
if not, the trans will log, DTC errors. for it.
but it's best to scan and see all errors.
there are are other issues, limphome on engine and transmission.
but the DTC errors show that too.