As an solo travelers you can visit many places:
1. Kerala (Munnar)
2.Himacha Pradesh (Trekking)
3. Outskirts of Pune (Mahabaleshwar, Lonavala, khandala lavasa, Imagica)
4. Can visit to Alibaug. definitely a very good place to relax and be calm.
5. Matheran (Maharashtra)
6.Goa but not that safe(Will prefer south Goa)
7. Panchmari (Madhya Pradesh).
9. Andaman and nicober (Scuba diving).
10. And a bike and mountain lover then Ladakh is the best place for solo travellers. I hope this will help you