Answer:
Here are the sentences changed into past tense:
1. I needed your help.
2. He sat down properly.
3. Somya wanted a glass of juice.
4. She wanted to marry Mr. Nikhil.
5. He came here regularly.
6. We played tennis every morning.
7. She wanted to be a dentist.
8. We generally sang songs all together.
9. Sujata called the ambulance.
10. He did his homework on time.