rameuniver wrote:
1) Is there any alternative solutions to make Client machines authenticated through Active Directory without rejoining to domain?
As others has pointed out the reason for lack of client access is that the computers passwords is changed every 30 day by default. If you have no more recent backup of the domain controller than about 6 months than only rejoin or computer password reset is possible.
It might be a bit late to point out, but Active Directory is meant to not be a single point of failure. You should always have at least two copies of the directory services database, i.e. two domain controllers replicating all information for load balancing and fault tolerance.
In your case now you might look at the netdom.exe command line tool. It is possible to join machines / reset machine password remote if you know the local administrator password. This might save you some time instead of physically rejoining every pc.