A) Last night I ____ (lost) my keys - I had to look for them.
B) I ____ (lost) my keys - can you help me look for them?
C) Last night I ____ (lost) my keys - can you help me look for them?
I know that for question A we use Past Simple because we know the specific time the action was completed.
Answer A: Last night I lost my keys - I had to look for them.
For question B we use Present Perfect Simple because the specific time the action was completed is not mentioned, and the consequence of the action is visible in the present moment.
Answer B: I have lost my keys - can you help me look for them?
So! The question C is a combination of question A and B. What tense should we use?