What to do if brokerage did not provide cost basis for two stocks? Does it mean thatI can’t e-file on Turbo Tax without filling this in?

you'd have to ask them. perhaps the securities were transferred from another account or your personal holdings to the account in which case the broker will not have the cost basis. it would be up to you to provide the figures, 

If you know when the stock was purchased, check here for some tips on how to find stock's cost basis.