Can i file carryback loss for 1256 contracts for amendment in turbo tax?

Yes, you can. 

When you're amending your prior year return in TurboTax Online:

1. If you don’t see [Prior Year] TAXES in the left pane, select the dropdown to the right of Income & Expenses on the Hi, let’s keep working on your taxes! page and then select Let’s get started, Pick up where you left off, or Review/Edit. 
   • Otherwise, in the left pane, select Federal, then Wages & Income (This is labelled Income & Expenses in TurboTax Self-Employed)
2. Scroll down and select the Show more dropdown to the right of Less Common Investments and Savings 
3. Select  Start or Revisit to the right of Contracts and Straddles
4. On the  Any Elections? screen, select Net section 1256 contracts loss election, then select Continue
5. On the  Contracts and Straddles page, select Section 1256 contracts marked to market, then Continue
6. If the Section 1256 Contracts Summary screen generates, select Edit next to the account
7. On the  Section 1256 Contracts screen, enter your information, selecting None of the above next to Special Handling, then select Continue

See Loss carryback election in the IRS' Publication 550 (2022), Investment Income and Expenses for more information.