If you staked Lavita tokens from your Theta Wallet, either web wallet or mobile wallet, and they suddenly disappear consider adding them first, click on ADD TOKEN and use the following information:
Ticker symbol: LAVITA
Decimals: 18
Token address: 0x46fBF4487fA1B9C70d35BD761c51c360dF9459ed
After that click on STAKE again next to Lavita tokens, even if the balance is zero you should be able to see your staked Lavita tokens and rewards.