How do you locate draft messages

They should be in the Draft folder for that particular account.

Tap "Mailboxes" in the upper right corner to get to the list of mailboxes. If you have more than one account, tap on that account to see the list of mail boxes. Tap on Drafts. I only have one account on my iPhone at present. Drafts is the first item below "VIP".

The Messages app doesn't save drafts. If you started a message but didn't send it, it should still be at the bottom of the conversation in which you were typing.

In that case, I'd suggest you start a new thread asking for help with the fact that Messages is crashing. Resolve that underlying problem and you won't really need to worry about losing messages.

Best of luck.