I have a Magento store which hosting information are missing. I can login into the admin panel and want to access the module files from there. Can I do this?
No, and for good reason. This would be a huge security risk.
There once was a free file manager extension that you could install via Magento Connect from the admin panel and then edit all the files (if file permissions on the server were not preventing it)
This extension has been used exensively by hackers who now just needed admin access to install any malware on the server. After that became known, the extension has been removed from Connect.
So what should you do instead?
Contact your hoster, identify yourself, and let them send you new login information.
This is not there in magento 1.x for now. You can purchase this extension for the same. I have not used this one but seems to be popular.