one thing if you have a good internet connection like 3g of wifi then dont be afraid your all application history is saved in hotmail id's purchases hitory, in which all application are listed also purchased app!! reinstall it from thta list
in any upadte glance is not working in L520,coz it isnt having supporter hardware for glance!! In blk update glance is not working!! In India blk update is in waiting state for approval in L520!!