IRS Publication 501 Dependents, Standard Deduction, and Filing Information page 9 states:
You may be eligible to use qualifying surviving spouse as your filing status for 2 years following the year your spouse died. For example, if your spouse died in 2023 and you haven't remarried, you may be able to use this filing status for 2024 and 2025.
For the year that your spouse passes away you can file a joint return. For the next two years IF you have a qualifying child dependent you can file as a Qualifying Surviving Spouse. If you do not have a qualifying child then you file as Single.
Two years. But remember that you need a qualifying child. Full details here.
https://apps.irs.gov/app/understandingTaxes/hows/tax_tutorials/mod05/tt_mod05_07.jsp
Do you have a child? You can file a Joint return the year your spouse died. For the next two years following a husband's or wife's death, the surviving spouse can file as a qualifying widow or widower if they have a qualifying child. That basically lets you continue to use the same tax brackets that apply to married-filing-jointly returns. After the year of death if you don't have a child you file as Single.
Then to file Single you should start over and set up a new account for yourself and not transfer from last year. You will have to re enter any prior carryovers and depreciation, etc. manually.
See the eligibility rules on page 9 of IRS publication 501
https://www.irs.gov/pub/irs-pdf/p501.pdf
See Turbo Tax help article