If i dont know the purchase date or the cost basis of a coin, can I put cost basis as 0 and purchase date as current?

If i don’t know the purchase date or the cost basis of a coin, can I put cost basis as 0 and purchase date as current?

I don’t mind paying full capital gain taxes because I don’t make much. Just wanted to liquidate alt coin so I can simplify my taxes for future crypto and take any of my investment back.

It all good, I just went ahead and done it.