My company was sold. All employees were accepted by the buyer. I had 3 weeks vacation and used 1. I had 2 weeks acrued to use, not knowing the company was being sold. When I went to the new company I was given 4 new weeks vacation. Am I entitled to the other 2 weeks that I acrued from the old company?

Whether or not you would get credit for your accrued vacation from the other company would be addressed (or should have been) in the acquisition agreement. However, the prior employer may be required to pay out accrued vacation upon the sale of the business. See here:
http://www.dllr.state.md.us/labor/wagepay/wpunusedvacpay.htm

You can contact the state Division of Labor and Industry to inquire as to whether this provision applies to companies that have been acquired as well.