What would it be
My car has a manual transmission.
Hello. If your car will not start on its own, but will with a jump start, then the first thing I would check is the battery. If the battery is old or worn it may no longer have enough cranking power to start the engine. It may also be possible that the starter is the issue, if it is old or worn out as well. I would start by testing the battery, changing the battery if necessary, to see if this solves your starting issue.