Reset PW help requested

Hello,
I've read some posts and I've tried to reboot and command S after chime. The problem is that I don't get a chime and my volume is turned all the way up. I bought a used MacBook Pro 2012 and I have a call into the place but who knows if I will get a call back. I'm anxious to use my laptop but I don't have a password it is asking for. I tried my Apple ID and pw that didn't work. I did t set up a password because I didn't want to have this issue and now I'm desperate for help. Please tell me someone can help me?

Sincerely, Trish (forever grateful for any support)