How do i fill in the date on form 1098 with a date if blank on it from office

Assuming you are asking about a mortgage interest form 1098.  The box 3 date is the date the mortgage loan was taken out. Your lender will have that date for sure.  You can contact them to get the correct date.  You should also have it in your home loan documents.  

That date is used to apply potential limits to mortgage interest deductions.  If the loan was taken out before Oct 1987 there is no limit to the interest deduction.  If the loan was taken out between Oct 1087 and Dec 2017 then the loans over $1M have a limited interest deduction.  If the loan was taken out after Dec 2017 then loans over 750K will have a limited interest deduction.   TurboTax will calculate any interest deduction limitations based on your entries. 

Also note, if your itemized deductions do not exceed your standard deduction for your filing status the the interest deduction/form 1098 entries do not matter.   

For the 2022 tax year. The 2022 standard deduction is $12,950 for single filers and those married filing separately, $25,900 for joint filers, and $19,400 for heads of household.