It might help us to know whether you have a FOB or RKE type
FOB is the type that you insert into the ignition
RKE is the Remote Keyless Entry type
There are several things that can occur with either type
The battery is dead, this hardly ever happens.
If you open the FOB or RKE, there is a circuit board.
If you are going to check out the circuit board, do it over a table.
There are contacts that get dirty & can be cleaned with an eraser or que tip & alcohol or anything that does not take much pressure
Another thing that happens is that those little contacts become unglued.
I suggest that you watch a youtube video or two to see ways to adhere those contacts back
in place
If you only have one FOB or RKE, may i suggest that you get a spare
This company has brand new OEM FOBs & RKEs
They also have a 3rd device, it is called a Transponder Key, the Chip is in the head of the unit
i believe the devices are
$99.95 for Ram RKE remotes
$59.95 for Ram FOB remotes
less than $10 for a Transponder key
https://www.carandtruckremotes.com/
You can usually find a locksmith that will program the remote for $95 or less
ACE Hardware also has FOBs & RKE remotes & most of their stores have the Programming tool
Good Luck