Also, i don't understand why my shares disappeared? I haved 91091, afther few minits i have 91087...
Your "Round Shares" is how many shares you have inside last N shares (currently 2,480,200). So if you have been mining long enough with constant hash rate, you would see your "Round Shares" at about the same number, because your older shares (outside of last N shares) have expired. At the bright side - this # would still be the same even if the block is found. Your reward is also calculated based on your "round shares" inside last N shares multiplied by the block reward (currently 50 LTC)
Example: you have 91k Round Shares
Your reward would be 91K/2480K*50ltc= 1.83LTC if the block is found.
Exactly, and the reward is paid for each block found, so assuming you kept mining at the same hashrate, if we found another block in 3 hours, you'd get another 1.83LTC payout (assuming the pool hashrate had remained relatively the same as well).