Where can’t i find a needle clamp for a Necchi Supernova Ultra ? Having problem locating one, thanks in advance

There is a button with two "prongs" or wings. Rotate the prongs clockwise about a quarter turn, to face the square mark (Q in the diagram) then press it down. It will stay down. To raise the feed dogs, turn the prongs anticlockwise (to S in eh diagram) and it will pop up
https://www.manualslib.com/manual/1205574/Necchi-Automatic-Supernova-Ultra-Mark-2.html?page=7#manual

it would have been helpful if you had provided the model number of the Neechi sewing machine.

But if you go to this website you should be able to locate the correct part for needle bar clamp and screw.

Necchi Sewing Machine Parts

Most sewing machines can use a double needle, the one with the single mounting shank and it turns into two needles.
MAKE sure you have Zig Zag needle plate installed to accomodate the double needle.
Turn hand wheel slowly to test then use thread and fabric and turn flywheel by hand to test sew.

check this link for parts and see if it's what you need

http://www.sewingpartsonline.com/necchi-supernova-ultra-mark-2-sewing-machine-parts.aspx

Just measure the existing belt and go from there. Besides the supernova and supernova ultra are likely to use the same belt.

try sewingpartsonline.com

in Italy I have bought it by 25 euro :) - yesterday ;)
[email protected]

Try ebay for a parted out machine.