Limitation- equitable mortgage.

There is no limitation in your case. When your property is describing as NPA assets then bank will take action against your property at any point of time. 

the limitation is 12 years from the date of last payment or acknoledgement of your debt either by way of revival letter / debit balance confirmation etc. as you have not stated when you have last acknowledged the debt either by way of part payment or in writing. we can not say whether or not claim against you is in force or time barred.