I dont know which file i deleted,But now i cant open the sambapos 5 now

just now, i going <user/Documents>deleted some files, but now i cant open sambapos 5 now,

after i press button

After i reinstall sambapos 5, the problem still there, please help me,thanks a lot.

sometimes server need to restart ,if you installed sql express ,try to login management studio, if it opens than something else, if management not logged in follow this, goto services and start server.

still can not, now i delete all SQL relate software and sambapos5 , i will reinstall again

Seems very specific with login failed rather than something else like database connection string error if SQL was not running!
If your reinstalling be sure to used mixed mode auth as Windows auth only seems to often cause people problems.

Thx,after i copy two files from another computer, the problems fix already.