Have looked up ferplast 80 aquariums online as this is one i have not seen before.
I have managed to find a manual for a Ferplast Dubai 80, not sure if this is the same as your tank and filter, but am sure it will be similar.
Checking the pump at least every 6 months and cleaning it when necessary in the following way:
• remove the hatches and slide the overtank lamp to access the pump compartment:
• unscrew the filter top;
• remove the pump unit, adsorbent sponge and return pipe from the filter, pulling it upwards (13);
• remove the pump from the return pipe, remove the front section and remove the rotor (14);
• remove any lime scale or impurities with the soft brush BLU 9037 (never use detergents or chemical substances);
• re-assemble the unit following these instructions in reverse.
IMPORTANT.
The biological materials should not be washed. Therefore, we suggest never removing them from the
filter so they retain their active bacterial properties
Quoted from -
http
/www.ferplast.com/store/media/catalog/product/docs/0040000394.pdf
So i would suggest trying to take the filter apart again and double checking everything is as it should be and reassemble carefully and ensure there is water inside the filter and pump housing etc as CSnyder mentioned, sometimes they need priming to get started.
BTW the rest of the instruction manual talking abour replacing filter media every 6 months etc, ignore that, its basically a money making way of getting you to buy more of their products.
The only thing that may need replacing is activated carbon which should only be used if treating the tank with mediacations, all other times, no need for carbon in the filter.