I miss you a lot. I haven't seen you for two months. It's a long time and I want want to see you once again to talk to you about everything.
I have heard that you have had a bad accident and now you are in the hospital. I heard that yesterday and I decided to write you a letter. Now I'm so hopeful to see you again and I hope you have a speedy recovery and I wish you be healthy again.
Let me write short and I wish see you soon.
thanks dear teacher
If I were a native speaker of English, I would never shut up. :-)
In British English we say 'in hospital', not 'in the hospital'
I hope you have a speedy recovery (and are soon healthy again).
Your last sentence is unnatural. You might consider something along the lines of: This has been just a short note to wish you all the best. I hope to see you soon.
I have heard that you have had a bad accident and now you are in the hospital.
Correct me if I am wrong, but I assume the accident was over. So should I place (I have heard that you had a bad accident and now you are in the hospital) omitting have?
No- the accident may have finished, but the injuries that resulted are still relevant, so the present perfect is fine.