I'm pretty new to Macs. On a High Sierra OS I accidently renamed the startup folder (which is a subfolder under "User's iMac (564)") thinking it was for an external drive I had added. It is now not a subfolder under User's iMac (564). I had not set up Adm. password. I have not rebooted since this happened. Will this prevent booting now, and if so how can I fix this? Thanks.