1) file police complaint of criminal trespass under section 441 of IPC

2)441. Criminal trespass.—Whoever enters into or upon property in the possession of another with intent to commit an offence or to intimidate, insult or annoy any person in possession of such property, or having lawfully entered into or upon such property, unlawfully remains there with intent thereby to intimidate, insult or annoy any such person, or with intent to commit an offence, is said to commit “criminal trespass”.

3)also file declaratory suit that you are owner of land

4) seek injunction restraining trespasser from disturbing your possession of the land

At the moment who is having possession over the disputed property? In case you have possession over the property(even if constructive), file an injunction suit and obtain an order of status quo.

File a police complaint regarding it...

You should understand the legal position.

The purchase of an immovable property shall always be vide a registered sale deed only.

The revenue records cannot confer marketable title to the buyer.

You may however issue a legal notice to the claimant instructing him to refrain from interfering with your possession and enjoyment of the property.

You can also file a permanent injunction suit restraining him from interfering with your possession and enjoyment of the property on the basis of documentary evidences in your possession.

If he is still indulging in any type of illegal acts you may approach police with a criminal complaint against him.