Yahoo mail account unable to sync with server

hi, i've been locked out of one of my Yahoo Mail accounts since 11/11/16, got warning symbol next to linked account: "unable to sync with server".

since then have not been able to login to account. finally unlinked it from others, but now cannot login or relink.

pw recovery keeps allowing me to sign back in to other accounts with different ID name, but not the one i put ID for.