Hey before this gets way out of hand and you start removing wheel nuts to try a fix the door handle lets look at this logically.
The car has 2 doors so if something is not working on one side try the other to confirm.
1. First try the buttons on the keycard to unlock, lock the car that will confirm battery power in the keycard, If you have 2 keycards try both.
2. Put the keycard onto the middle of the drivers window and try the handle to lock and unlock, then go to the passenger side put the keycard on that window and try the same functions. And if you want go to the boot and try the same tests there.
( From this you will know if it is the handles or the keycard but if the keyless entry works on one side then the keycard transponder is working and if the button does not lock it on the handle then it's the handles button that's faulty also make sure your hand is not behind the handle when your pushing the lock button on the handle )
By now you will know what's wrong a new handle is around £50 and there is a how to guide on the site of how to change it if you have the tools and skill level, if you pay the £5 membership fee for a 1yr you will be able to view it.
The handles like mine can give button trouble just after washing but when dried out can start working again the rest is up to you
good luck.