bither website down, for sale? so what is a good bitcoinx wallet.
what if i lost my wallet password of the bither wallet? how to remove and reinstall,
with seed? i guess. i dont even know if that is there.

Website is not dead, working fine for me, and code is Open Source so you can can check and verify it or ask someone else to do it.
I checked both android and ios versions and they are last updated on September and desktop version last update was on April.
I also know that they have shifted more to BitpieWallet and BitHD hardware wallet (Trezor code) and they are very active on social media and you can ask them anything you want.

Bither iOS/Android v2.0.2 released
1. Fix bugs;