[Q] Can't start my HTC One topic

Hi guys I'm new on this forum and I hope this is the right place to put this thread.

I wanted to try the Cyanogenmod with my HTC One and got it installed and working properly but then I decided that the mod was not for me and I wanted to go back to the normal os, now I dont have any os at all and for some reason I can't start the cyanogenmod again, I have read a lot of threads and guides on how to fix this but I haven't found the right thread for me so I thought I would start my own. I should also mention that I tried a lot of these fixes and probably made the situation worse but I hope I can still fix this.

What do you need to know to possibly help me and what do I need?
And since I'm completely new on everything related to anything please explain things as simple as possible :)

Thanks in advance!