to assist with your issue, the only possible way of moving that many messages is to again - install an email client/program - and move them all to inbox. the only way i know of doing it through the gmail web interface is to go through them page by page, select all, and move them... many hundreds of pages :)
however, IMAP does not work correctly with gmail (at least in outlook and 99% of clients out there) this is due to gmail's implementation of IMAP (X-GM-LABELS extension). it will not work correctly. at all. your only option is to use google app sync (monthly cost, data collection), or switch to a proper IMAP provider. -- You received this message because you are subscribed to the Google Groups "Gmail-Users" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. Visit this group at http://groups.google.com/group/gmail-users. For more options, visit https://groups.google.com/d/optout.
