Sentence inquiry

AnonymousIs the word had necessary?

If you use 'could have', yes.

AnonymousAlso did I use could correctly?

Yes.

Then how could the sentence be changed and it would be ok to not use 'had'?

AnonymousThen how could the sentence be changed and it would be ok to not use 'had'?

You cannot and still refer to the past event.

I see. I have one more question!

Would it be correct to say: If you 'have' asked me, I could/would have helped. I am assuming it is possible, but the use of 'have' would indicate that the event occurred in a more recent past time. Am I correct?

Many thanks.

AnonymousWould it be correct to say: If you 'have' asked me, I could/would have helped. I am assuming it is possible

No, it is not possible.

Anonymousthe use of 'have' would indicate that the event occurred in a more recent past time. Am I correct?

That is correct and it creates a temporal conundrum as to what happened when.

Aha, thank you. What about: You should have asked me, I would have helped you or I would have been able to help you.

I hope these options are possible otherwise I would have to go and teach myself the basics. Sorry to bother you but that should be my last question of the day.

Anonymous What about: You should have asked me, I would have helped you or I would have been able to help you.

What do you wish to do with those phrases? I need the complete sentence that you are considering.

These are the complete sentences:
You should have asked me, I would have helped you with your project.
You should have asked me, I would have been able to help you with your project.

Just checking if they are grammatically correct?

You should have asked me; I would have helped you with your project.
You should have asked me; I would have been able to help you with your project.

AnonymousJust checking if they are grammatically correct?

As re-punctuated, yes—they are good.