Minecraft will not open because i deleted files and dont know how to get them back

i keep trying to open minecraft and keep getting this message Unable to locate the Java runtime. Error details: Undefined error: 0 Filename on disk: Path: . Exists: Directory i might of accidentally deleted files from the minecraft launcher and do not know how to get them back i would like a solution, Ive tried redownloading the minecraft launcher 10 timnes and have reinstalled java i cannot get this to work.