mac stuck on apple loading bar after clearing hard drive

Hey,

so I have a 2012 Mac i7 16 gb ram 1tb. I have erased the hard drive and I think I may have deleted the os from utilities when booting. I tried to get it working a while ago and gave up so I can’t remember exactly what I did. However now when I turn it on it just boots onto the apple loading bar and gets stuck at 100%. It won’t let me get into utilities or anything. Is there anyway I can get into utilities or the correct place so I can re-flash the os back into it. Thanks in advance