You can go To Goa;I visited the goa in Dec 2015.The beaches are decorated like a bride.At that time;the famous Sunburn festival also get organized there.You can go to cruise for the parties.And away from the beaches is peaceful,clean,less crowded area i.e. South Goa.Hire A scooty and wander all tha goa with the help of google maps.In other options;you can go to Jaiselmar and Rann of Kutch. Or if u want to see the snowfall go to Shimla or Manali. If you have more than a week then 1)Delhi->Bikaner->Jaiselmar->Mt.abbu->Delhi 2)Delhi->Chandigarh->Shimla->Manali->Amritsar
3)Delhi->Chandigarh->Mandi(Himachal)->Parvati valley(Malana,Kasol,Kheerganga trek)->Manali->Delhi
Hey Mani, There are lottt of options and Places to travel solo in India .... Karnataka - Hampi and Gokarna Tamil Nadu - Pondicherry and Tanjaur Kerala - Varkala and Wayanad Maharastra - Ajanta and Ellora caves Gujarat - Lakshmi vilas palace and Rann of Kutch Rajasthan - Udaipur and Jaipur Madhya Pradesh - Khajuraho and Shanti stupa Orissa - Puri and Bhubaneshwar Himachal Pradesh - Mcleodganj and Dehradun Uttarakhand - Rishikesh and Nainital Punjab - Ludhiana and Amritsar Uttar pradesh - Varanasi and Bodhgaya West Bengal - Sunderbans and Kolkata Even delhi, gangtok, meghalaya, many more ... and many more ... You can check thousands of solo blogs on Tripoto blog pages .. Travel solo and enjoy buddy ... Happy Travelling !!!
Hope you realize this is extremely vast question! There are thousands of places and India is vast. Without even knowing where you are from or what you have seen, not sure how to answer that. Please try to be more precise so that people can genuinely help you and others can benefit from the answers too