If I haven't driven a car in months and I can't start the car...

...and I can't charge the battery, is the battery the reason that the car won't start?

Take it out, see if you can get a ride to an auto parts place who will test it for you.

they will lose their charge if remained undriven. :(

A good jump (from another car's battery) might help it.

I'm pretty good with cars, but more info would help.
When you turn the key in the ignition, what happens?

It can't get jumped or charged.

You'll have to jump or replace it.

now you kmow why it is prudent to start those darn things every so often. :D

It may be able to be jumped.
Don't be impatient if trying to jump it from another car.
Give it a few minutes to get some juice before trying to start your car.
Remember the obvious, + to + and - to -.
:)
Good luck.

Not enough.

If absolutely nothing is happening after being jump connected for 10 minutes, then you might have a loose/corroded battery connection.

However, by nothing, I mean NOTHING. Engine never turned over in the first place, never started to turn over. No clicking in the engine compartment when the key is turned in the ignition.

If you are getting some clicks after trying to jump for 10 or more minutes, but not enough to turn the engine over, you might just need more patience, or you might need a new battery. They do loose their charge over time without use, and they can be killed by, for example, being left for several days with the headlights on.

Hope you find the solution.