Repairing pulled back corners

Thank you all

The only thing I would add to fourthclassC's advice would be to remove any old caulk that's there. Plastic scrapers won't scratch. Eternabond is a pain to trim, so go with a 2" roll if possible. Be sure to use a roller on the Eternabond and to clean all surfaces first.

my suggestion. Remove any dislocated aluminium trim. Bring siding/wall back into shape using Gorilla glue if needed. Caulk all corner joints (vert. and horiz.) with Proflex. After curing cover corner with correct width (trimmed ) eternabond. Re install corner trim with thin bead of proflex on the inside.
Screw corner trim back on with stainless screws or what some stores call shutter screws which are painted heads (usually white) and stainless. Install or not the plastic insert that covers the trim screws.

If it's just the aluminum corner molding, you should be able to get it back in place. There are screws under the vinyl trim strip. Pull back some of the strip that covers the screws and bend the aluminum molding back in place and re-screw it. You'll might need to drill new screw holes so the screws don't go back into the old ripped out holes. Once you get it back in place, you'll need to re-caulk it. Don't use silicone caulk as nothing will ever stick to it in the future, not even more silicone.

Pictures? Easier to tell what needs done if we can see the damage.