1. For unauthorized sale of "reserved category land", represent before the district collector, with proper documentary evidences and request for confiscation of said land and initiate prosecution on both parties.
2. For other matter, You can file a Police FIR, requesting investigation and charge-sheet, for offences like Cheating, Intimidation, Fraud, Breach of Trust, Mischief etc.... against the person/s, supported with all relevant supporting Documents, Evidences & Witnesses.
3. IF the Police does not take action, THEN you can file private criminal case u/s 156(3) Cr.P.C., in the local Magistrates court, seeking directions to the Police to investigate and file charge sheet. The said Person may come down for settlement.