I am migrating my coworkers from using GoDaddy email to Office 365 Business Premium.  

For one of my coworkers, I forgot the step of exporting a .PST backup file before I deleted her GoDaddy account in Outlook.  But I still have the .OST file that Outlook created while connected to her GoDaddy account. 

Now that I've changed the MX records in GoDaddy, it won't let me reconnect her Outlook to restore the connection to the OST file. 

Is there a way to import the OST file on her computer back into her Outlook under her Office account?  Or somehow convert it to a PST file?  

Thank you in advance for your time and assistance. 

Now that I've changed the MX records in GoDaddy, it won't let me reconnect her Outlook to restore the connection to the OST file. 

Just for the sake of accuracy - if you were able to connect to the GoDaddy Account, would not reconnect the existing OST file - would recreate it and mirror the contents on the server.

In terms of recovering the current OST file - your only option is to do a search for a 3rd party OST2PST tool (or wait a little while and there should be lots of people suggesting their products). Whatever you decide to use - make sure you test it prior to any purchase.

" it won't let me reconnect her Outlook to restore the connection to the OST file. "--

It's an IMAP account, right? If this is the case, the emails are actually kept on remote email servers, delete the account from Outlook should not delete the data from the mail server. Once you reconnected to the account, the data will be available again.

Or actually, you are not able to connect to the account any more after changing the MX records? 

Regards,

Ethan Hua
TechNet Community Support

In such case you would require Outlook data file converter tool which can convert your ost file to pst. However, there is huge market of software vendors who offers 3rd party software. But my personal experience as well as suggestion - Try Stellar ost pst converter tool. All the utilities of Stellar are totally worth. If you're interested, try stellar ost pst converter demo version for testing.