I was driving around and after stopping, my key fob just died, no buttons respond apart from the little red light blinking, replaced battery but didn't help at all.

As my door lock is stuck I have no way of locking my car, what could've caused it to stop working??

Unless the keyfob has died electrically (did it get wet??), the electronics should be bullet-proof.

 

Make sure the CR2025 battery is new and that the contacts on the battery terminals are tight and not loose (because that would make the keyfob stop working).  Also make sure that there is no corrosion on the +ve or -ve terminals and if there is, wipe it or scrub it off before putting in a new battery.

I've used a brand new battery and I did check the little contacts, a bit worn out on the positive gold plate but that's not corrosion and just scratched of, and it did not get wet as it stopped working after I was driving.

I think it's something with the car rather than the key, because it started working again randomly. Hope it won't decide to shut of after I lock my car somewhere not close to home...

Been there, done that.

 

I thought I was going to be stranded but walking around the car pressing the unlock button eventually opened it without the alarm sounding when physically using the key in the lock.

 

I put it down to freak RF interference preventing the key signal from being received correctly.

 

Now you know the physical lock is stuck, get a can of WD-40, insert the straw in the lock and give it a good scoosh.  It may free up instantly or require time, more scooshes and key insertion/wiggling.