Is there a way i can make my computer play song when it boots up?

you means logging screen or after logging ?

Go to run type = regedit

Hkey_current_user

AppEvents

EventLables

WindowsLogon

(ExcludeFromCPL) open and make Value 0 and click ok

Open control Panel/ Sound/ go to sound tab/ remove the tick play Windows start that choose ur custom file. make sure song convert it to wav.