Dear Jitender Kumar:
1) How do you know that the chq book got lost on 23.04.13? (just curious to know)
2) If you can prove that the signatures on the chqs are forged, then the bank is liable and has to compensate you. This is regardless of whether (a) you have been careless in safekeeping of the chq book or not, (b) the forged signatures cannot be identified as forged even by close examination with the naked eye. At best the bank's lawyer will try to prove that you were careless - so what? Banks have no mandate to debit your a/c when the signatures are forged, so the bank will have to compensate you - as simple as that.
3) On the 1st query about a year back I'd like to add: the main issue is not if it is a self chq or not, the main issue is whether it is a 'bearer' chq or an 'order' chq. Since it was a bussiness/current a/c, I think that the chqs were issued as "Pay ... or Order" rather than "Pay .... or Bearer", as is the practice in most Banks. If it was an Order chq, and the chq was encashed by writing Self so as to make the chq as "Pay Self or Order", then if the signature of the a/c holder has not been obtained at the back of the chq, it is a SERIOUS LAPSE on the part of the Banker/Cashier, This is because sec 48 fof NI Act says that "... chq (payable to order) is negotiable by the holder by indorsement and delivery thereof". If there was no sign of the a/c holder at the back of the Order chq, "indorsement" did not happen and so the payment was "not in order". The bank is liable to compensate the loss to the a/c holder for wrongful payment. However, if the chq was a "Bearer" chq and was written as "Pay Self or Bearer", then it is not mandatory for a/c holder's sign on the back of the chq, because as per Sec 47 of NI act, ".. chq payable to bearer is negotiable by delivery thereof". Hence, no indorsement (sign on the back of the chq) is legally required.
Needless to say, regardless of whether it was a Bearer or an Order chq, or whether sign on the back of the chq was there or not, or whether the a/c holder was careless or not, just by proving that the sign on the face of the chq is forged is more than enough for the bank to compensate the a/c holder.