is phpMyAdmin available? - open up db and go to "SQL", you can upload it there.
if not, is console access available? ftp up the file, go to mysql shell, connect to your db and run the export script with .FILENAME.txt.
!! this works only if you exported the database as "SQL INSERTs" (not raw data, comma-separated) !!
in all other cases, you could upload the .txt file and write a php script that reads in the data and executes inserts. (this solution is most work)