Also try in a different location, it may just be a network issue.
If you still have a keyboard problem it may well be a phone issue, if you know anyone who would let you try your SIM in their phone, this will determine a phone or SIM issue.
If problems continue, you will need a replacement phone or a repair (if possible).
When you send a text message at the bottom of the keyboard you will have a button where you can change from letters to symbols, you have probably accidentally pressed this and changed the keyboard to symbols, try tapping the abc letters, it should change back to alphabetical order.
to edit my reply. I hope this solves this for you @sleepyviolet , you have probably only changed the keyboard mode, this is the key you use to enter a £ sign or an alternative symbol such as @.
