So I took my ranitidine medicine at 12pm and drank half a cup of alcohol at 11pm would that have caused a lot of damage towards me? I'm worried

It is possible. If you are taking ranitidine, it is most likely because you have a problem with your stomach such as gastroesophageal reflux (heartburn) or ulcers. You should strictly avoid alcohol if you have either of these conditions. Alcohol lowers the pressure of the valve (sphincter) that keeps acid from coming back up into the esophagus. Alcohol can cause bleeding from your stomach or esophagus.
No. But listen, buddy. This is more alcohol than you need to be drinking, and you are a teenager anyway. Exploring and making mistakes are normal at your age, but you might have really made yourself sick or done something dumb just from the alcohol. Be nicer to yourself.