No chimes at start up

[Tom B]

Hello. I know this will annoy you all who have answered this subject in the past but help would be appreciated.
Im running 10.10.3,I have no start up chimes, i need to solve a verification problem and have been told to start mac and press command R,but I have no chime. I have been told to reset pram by holding down command, option, P and R but still no chimes and all that happens is a big padlock on a grey background with no mouse use.Please if you can help I need it. Thanks

 

[Cory Cooper]

Hello and welcome.

No question is annoying around here, so no worries.

-Which model Mac?

The padlock usually means there is a firmware password on the Mac. Can you get past that screen by entering a password?

To remove the padlock/firmware password:
What is a firmware password and how do I set one up?

Try following the PRAM reset instructions here:
OS X Yosemite: Reset your computer’s PRAM

Since you have no startup chime currently, power off the Mac totally. Press power and immediately hold this key combos before the Apple logo shows on the screen. You may have to remove the firmware password first, before attempting the PRAM reset. Also, if you startup normally, when you see your desktop, do the volume controls work and do you have sound?

C