I had a similar problem with a Cobra Optica putter, - bag blew over with putter clipped to the side, landed with full weight of bag + force of wind on the mallet end of the putter head. My putting went to complete 5**t for a few days after, until I twigged that the putter face was closed at address.
The Pro at my club said he could re-align the grip, but didn't want to mess about with the shaft. Foolishly took it to AG where I'd bought it 6 weeks before, they couldn't do anything with it.
With nothing to loose I had ago myself,- gently warmed the shaft up to a very dull red with a plumbers gas torch, at the bend in the shaft where it is shaped to give the correct lie angle and twisted the head back into a square position.
The putter is fine now the only visible after effect is a slight 'blueing' of the chrome at the point I heated it.
My putting is still 5**t but the putter is OK