Land forcefully used by third party

No other go.  You have to move to court.

You have been dispossessed illegally so you need to file suit for possession u/sec 6 of Specific Relief Act.Court has to decide the case within 6 months and may pass order to  restore your possession .

You cannot ignore the legal procedures if you want to secure your property.

You have to lodge a criminal complaint against the intruder for the offences of criminal trespass subsequent to which you can file a suit for permanent injunction or bare injunction against him to restrain him from interfering in your possession and enjoyment of the property.

Even though the civil suit takes a little more time, that is the best option before you or you may have to indulge in illegal criminal activities against the intruder, for which you may have to pay heavily, sometimes you may be arrested for such unruly or violent activities. 

Very well analysed, opined and advised by learned experts, I endorse.

You have no alternative but to seek necessary relief (s) from competent jurisdictional court ONLY.

You will have to take stay against the mortagor as well as repossession immediately and file a police complaint for tresspass and other offence(s)..

It would be appropriate to consult and engage a local prudent lawyer for proper analyses of facts / documents, professional advise and necessary proceeding.