Weird Grinding

I tried to start my care this morning and it didnt start at first then when i put in gear there was a loud grinding underneath the car and so i put in drive and the same grind any ideas? i dont knwo anything about cars please help !!!

Gee I hope your starter didnt stay engaged.. Elsewise, Transmission fluid low or bad, Power steering fluid low, or pump failing. You say UNDER the engine.

Bass
Do you have any missing cats in the neighborhood?

i went to start it this morning and it wouldn't turn over then on the second try it turned over then sounded like a grinding from underneath the car then i put it in gear and and the grinding continued so i shut it off , but it grinded while it was in neutral and then also in reverse and drive. it was all good yesterday