how to do i enter 1099 B info when date acquired is missing and cost basis is missing?

You have to do some research to determine when you acquired the investment and how much you paid for it. If you know about when you acquired it and it was a publicly traded security, you may be able to find the historic market price by entering a search online using the name of the company.  

Also, you only need to know if it was held for more than a year for it to get long-term capital gain treatment, so you can pick an acquisition date beyond a year from the sale date if you know you held it for more than a year. You can also enter $0 for the cost basis, but you may pay more than you have to in taxes if you do that.