Error message read the following: do not see this type of error on the blog with link above.
Will try dropping the Consensu.db and reloading. I was late to update so maybe I am stuck on a fork.
what do I need to delete to reload the blockchain but keep my wallet keys?
A critical error loading Sia has occured: Siad unexpectedly exited. Error log: Loading...
(0/6) Loading siad...
(1/6) Loading gateway...
(2/6) Loading consensus...
Closing gateway...
difficulty adjustment hardfork incompatibility detected
That error is one of the described in that link. Close Sia completely (in Windows, clock close on "Close" on the system try icon), delete the consensus folder, open Sia again and let the client to sync the blockchain again.
By this way you are just deleting the blockchain. Your recovery seed will be always good to recover your funds. In this or in any other computer