after i dump my keys and import it again i have only coins from 2018-04-20 , and i was staking till 2018-07-01
where is my coins i staked for 3 months ?
try this
go to your old wallet (doesn't have to be in sync) and type this on the CLI:
listaddressgroupings[Enter]
then maybe you will have some new addys co check

-- always backup your data before you f*** with it

Its also possible they were staking on a fork. It sucks and is part of life with current blockchain tech, all you can do is try and check in on your staked address/s every so often and be ready to resync the chain if it looks funky. You don't have to access your stake server, simply add a bookmark to an explorer/your address and check on it every so often.
https://chainz.cryptoid.info/dope has an api you can use to pull address/pricing/etc into a sheet if your so inclined.