My ipad air was bought and activated AFTER September 1st and I downloaded pages, keynote and numbers. I then changed my Apple ID as the password no longer worked, these apps were also deleted I order to be updated. Now I cannot get the free version. Help?

My ipad air was bought and activated AFTER September 1st (activated December 25th) and I downloaded pages, keynote and numbers. I then changed my Apple ID as the password no longer worked, These apps had to be deleted as I needed to update them. Now I cannot get the free version on my ipad. I have searched the internet to see if there is a solution, and I found a few but unfortunately none have worked. I desperately need these apps as my iPad is used for school. Is this an issue I should take up with the apple support centre or something? Please help! Thanks