Won't go into gear
is this an auto or stick shifted car, ??? we can not guess this, ever.
you said, Gear, that is stick shift and A/T has no gears.
it has, R, D, 1,2,.. selections... are all 4 dead.?
shudders?
starts,
is RPM 800 or more?
you then shift to say reverse...
and step on the throttle , RPM is 800 and it advances to 1500 or more
and car moves,
does RPM go above 3000 and not move
that means , the tranny (or TCM or sensors) are bad.
if your RPM goes to 2000 and is stuck there, and car will not
move in any shifted rage, 1,2,D,L, then the brakes are iced over.
the key to this mystery is RPM. the engine RPM will tell you
what is happening,
for sure.
post it. and we can tell you.
slipping is when the tranny allows RPM to be unlimited at right foot actions.
if the brakes are frozen the RPM will be at the TC clutch stall speed
that is , about 2000rpm max and will shake there. (5sec max doing that)
see the FSM on stall speed, of your A/T
if this is a clutch car, say so, M/T stick car, say so, that be DIFFERENT/