Hello, meganfharvey.
I understand that a couple of letters on your iPhone keyboard aren’t working? I can believe that it is hard to get much done without complete access to the alphabet and would like to help. You have already done some very intuitive troubleshooting steps already. Nice work.
I did want to ask if you rotate your iPhone, do those letters then work on the keyboard? Does the issue follow the two keys?
To clarify, are the same two spots on the display unresponsive regardless of whether the keyboard is there or not? If this is the case, please check out this support article: Get help with the display on your iPhone, iPad, or iPod touch. If, after following the steps, the display is still unresponsive, please contact Apple Support.
If the issue is specific to the 'b' and 'h' keys even when rotated, that would be quite unusual, especially considering the troubleshooting steps you have already performed. Do you have any third-party keyboards installed? Is your iPhone up-to-date? From reference, I’m including an article that talks about the keyboards settings on your iPhone, iPad, and iPod touch.
I hope this information is helpful. Please let me know what you find out.
Update your iPhone, iPad, or iPod touch
Best Regards.