I had contributed $1800 to a Roth IRA for the year of 2021. I had to withdraw $550 of it during the summer but I want to contribute that amount back to the year of 2021 if it is possible. I use Fidelity for my Roth IRA and when I select transfer it only gives information about 2022 contributions. I want to know if I can still put my contributions back for the year of 2021
If you withdraw money from your IRA, you have no more than 60 days to put it back before it is final. This is called "indirect rollover". You can only do one indirect rollover per year, at most.
Once the 60 days passed, you can no longer "return" it, you can only contribute new funds. Funds can be contributed during the year to which the contribution is attributed and up to the tax date (before extensions) of the next year. I.e.: for 2021, you could only contribute new funds until April 18th 2022 (April 15th was a holiday in DC).
Of note is it doesn't actually make a difference. Even after the 60 days, but before the April 2022 cutoff, you still could have contributed up to $4200 more for 2021, so whether you call it "putting $550 back" or contributing another $550 for 2021 wouldn't have mattered. Since we're in October now you can't code anything for 2021.
You can still contribute up to $6000 for 2022, and unless you are planning to max that out and wish you contribute even more than that, it also doesn't matter that you missed the window for more funds in 2021.