For date acquired, type various in the box.  As for your basis, I suggest contacting the mutual fund company or brokerage firm for help in determining your basis.  As a last resort, you can enter zero for a basis, subjecting the full proceeds to taxes.

It is your job to track your basis in a mutual fund.

See IRS Pub 550 Investment Income and Expenses
page 44 Table 4-1 for a sample table showing
the basis records that you should have been maintaining.
The text in that section describes how to track your basis over time.