Aerial has snapped off

if it is electrical then it rises when the radio is turned on or if the radio is left on all the time ,when the ignition switch is turned on
it needs a separate earth point to operate and because it is a separate power wire ,there will be a fuse in a circuit that controls the circuit
because they are at the base of the antenna , they can fill with water and become inoperative through corrosion and such
have a radio technician or auto electrician check it out
if it is manual it may be pushed too far down and the tip is locked in
release the lock with a hair pin ,paper clip or similar object then pull the aerial up

It's probably bent or the motor is broken(motor itself or fuse). You should try getting it replaced. An electrician could tell you more or a service shop.

dealer[most expensive] auto parts store--online--or junk yard [are the cheapest]

It is usually best to check an aerial from the radio end with an ohmmeter or continuity checker. The aerial cable is a coaxial cable with a centre core that carries the signal and an outer braid that when properly grounded keeps interference to a minimum.

Measuring between the centre and the outer there should be an infinity reading on an ohmmeter, indicating no short circuits in the cable or aerial base. Measuring between the outer and a good ground the reading should be very low, no more than a few ohms indicating a good ground connection to the aerial base and of the aerial base to the bodywork.
The next test is simple and tricky at the same time as one lead of the meter will need extending. Remove the aerial mast and test for a very low reading of just 2 or 3 ohms between the cable centre and the stud or socket where the mast mounts. If all tests are fine it indicates the mast has an internal fault. If the tests aren't fine the cause is fairly intuitive.

To some extent you can perform the tests at the aerial base but the results will be limited due to the physical connection between the cable and aerial base won't be part of the test.

You need to be aware some installations are fitted with an aerial amplifier which can confuse matters and make checking more difficult.

cant find the car aerial cable from roof base

Another renault this is a american web site or so i get informed when i give wrong answer and assume a engine is a diesel and they dont sell the diesel version in america ,anyway i think you remove the light in the headlining and then you can get to it quite easy or was that the earlier one ,getting old and cannot always remember ,cant you get the old bit out with a pair of pliers by any chance

you unbolt it from inside the car behind a light in the head lining or something ,the aerial screws on as i remember so it should just unscrew and then change the mast

did the aerial rise up when you turned the radio on??

At the base of the antenna, take a small crescent wrench or pliers and unscrew the antenna from the mounting bracket. Any Chrysler dealer should have a replacement antenna.

U NEED THE GROUND SO IT CAN WORK