cannont get on line with windows live mail

For some reason I have lost the ability to go on line with my email account.  This happened whilst trying to find out why email backup with Acronis doesnt work.  Now I am unable to get on line at all with my email account.  I have tried reinstalling the software but to no avail.  In addition I thought I might try Thunderbird with Acronis so I loaded that and tried to transfer all my messages etc across but the system will not open or allow Thunderbird to open a tool for doing this with and extension of  .xpi.  Can anybody help please?