Nonexistent Java Runtime Environment

Ever since I downloaded JDK onto a flash drive into my computer, the launcher was acting weird. When ever I clicked Play, the launcher closed like normal, except the game never opened. Whenever I took the flash drive with JDK 8 out, the launcher didn't open and an error message opened that said this.

Launch4j

The registry refers to a nonexistent Java Runtime Environment installation or the runtime is corruptted.

The system cannot find the path specified.

I tried deleting .minecraft after taking out important folders like saves or resourcepacks, but it said that it was open in another program. I really need help fixing this so I can make sure my friends on my servers know I'm not dead (XD). I attached a picture of the Launch4j message.

Thank you very much.