Issue - Impossible to print  

Issue - Impossible to print

Sorry about the blast but I'm running in an issue with my Prusa MK3S (born like this, not an upgrade).
I experienced for the first time an issue with the filament. It broke just before the ptfe. I dismount the extruder, removed the ptfe (where the filament was inserted and blocked) and replaced it with a new one. However it doesn't work as expected. When I try to reinsert my filament, the filament is inserted and after a while (2 or 3 sec) I heard several sounds (something like "clack, clack") and it stopped without having anything coming out from the extruder. 
I may suppose that this is a common issue.. however I'm stuck with it and doesn't know how to solve it. I thought about changing completely the hotend but before going this way, I'd like to know if it might be possible to solve this issue easier. 
Thanks a lot ...