strange noise from engine/gearbox?

hi all,

just today when i was driving i heard a loud thump after which there's a strange rotating noise kind of like engine rotation kind of, when under acceleration the noise can't be heard and when decelerating while in gear 3,4,5 it makes the noise gear 1 and 2 while decelerating doesn't make the sound, and while driving if i just shift it to neutral while car is still in motion it makes the noise can slightly hear it but not as bad.

it's golf gti mk4 agu 2000

could something just be loose in the engine bay causing parts to touch or might it be more serious like gearbox/engine

just wanted some insights as i'm pretty clueless, will be taking it to the workshop tomorrow see what it might be

thanks.

was on my way to mechanic today and all of a sudden lost the speedometer and now the noise is louder even on idle i can hear the rotating noise like it's rubbing against something