Hey Amy,
Thanks for using Apple Support Communites! I see that you're having trouble with receiving texts from a single contact. I can help.
First, make sure that this contact hasn't accidentally been blocked from sending you messages. Here's how to check:
Go to Settings > Messages > Blocked.
From these screens, you can add or unblock contacts or unblock phone numbers.
To add a contact from Phone, go to Settings > Phone > Call Blocking & Identification > Block Contact. Then tap the contact that you want to block. To add a contact from Messages or FaceTime, go to Settings > Messages or Settings > FaceTime, scroll down and tap Blocked, tap Add New, then select the contact that you want to block. To unblock a contact or phone number, swipe left over the number, then tap Unblock.
Block phone numbers and contacts on your iPhone, iPad, or iPod touch - Apple Support
Let us know how that works out for you. Cheers!