The theme and plugins should be no problem - assuming you know what plugins were used and how they were configured.
You might be able to persuade the .xml import to run despite the fact that it won't be able to pull in any attachments (assuming the export included attachments). The only way to really know for sure is going to be "try it and see". Then it will be a case of uploading and re-inserting missing images etc.
If you do get the site back up again, do consider installing a decent database backup plugin - preferably one that emails you a backup file that can be stored offsite.