Failed to recover wallets, corruptions, and unable to reset

May i try reflashing my SD card with v4.9 before reformatting the drive?
If i have to reformat the drive(which means I have to download the blockchain again), can you give me some direction to do it?
I heard Windows OS doesn’t recognize Ext4, so I am not sure its a proper way to execute reformat using my laptop. I may have to do it through SSH terminal.
Any instruction is very much appreciated. Thank you.