1. On what basis you call it ancestral property?
2. What is the nature of the lawsuit filed by your neighbour? What was the outcome of the case filed by your neighbour? Unless your neighbour had any legal right in the property he could not have sued you.
3. The amount borrowed was only 3 lakhs. It seems that on default in repayment the bank took possession and auctioned the property. What was the market value of the property when it was sold? The sale proceeds could have been pocketed by the bank only to the extent of the amount due to it whereas the balance was to be remitted to you. Be that as it may, it was a blunder on your part to not to avail the legal recourse against the bank to stop it from auctioning the property.
4. There is no way you can get the property back after it has been auctioned except if you can prove that the auction was not held in accordance with the law.
5. The only right which you can now enforce is the right to get back the balance of sale proceeds, if any, was left after applying it towards the secured debt. So you must find out at what rate the property was auctioned. It may be added here that in a auction the property may be sold at a throwaway price.