It happened to me too. I installed the new pos recalibration version, when i replaced the previous wallet.dat of esp2 , it says error in reading wallet.dat and then just closes.
Make copy of your wallet.dat in safe place and start client with -salvagewallet argument
Sorry for being a nooob, but how do i do that :/
first go to your %appdata% file
to do this hit Win+R, Type "%appdata%" (without the quotations), locate your ESP/Espers folder, find the file named wallet.dat and copy it. and paste it somewhere you will remember. (not online as if someone else attains this they will have full control of your funds)
It is best practice to create a backup of this file semi-regularly saved in a few locations (all secure).
If you are posting binaries on a 3rd party hoster you should supply a checksum of the original file with it so people can verify that you are not giving them Trojan viruses. It would be better if Devs would upload a binary of the R1 wallet on their own server.
Rule #1 of computer security, do not run binaries that have been given to you by strangers from the internet.
For everyone else, trust third party software at your own risk, trust exchanges at your own risk, Cryptocoderz can stand by only what we deliver.
the majority of software and exchanges are more then likely safe, however you take a huge risk when you use these.
Even if the software is not malicious, even if the exchange is not a scam; these can fail and the person who trusted them will be the one to lose.
Good job dev ! 
