You say you deleted Hoster, you should not delete it, you should uninstall it while on line.
The proper way to uninstall Hoster or any MTU software is open Control Panel then Programs & features scroll down to Hoster, highlight it then select Uninstall making sure your connected to the internet. This would start the original .exe file, option would appear in that to uninstall.
Now if you did not uninstall from within that program you will not have freed up your registration to allow you to re install on new computer.
If you did deleted it there is a good chance you could recover it from the Recycle bin and then follow the instructions above.
Re installing, are you selecting your same version from the mtu.com upgrades page. if not hear is the link:
http://www.mtu.com/upgrades/hoster.htm
Click on get Hoster 54105 button then download the file.
Once downloaded find it (hoster541.05setup.exe) and start it.
Now if you cannot recover from where you deleted it or did not uninstall correctly it will probably tell you already installed on x amount of computers.
In which case you will have to submit that support ticket asking for a registration reset.
That can be found here:
http://www.mtu.com/support/contact-us.htm#HelpTicket
One other tip if you manage to recover it from the recycle bin, before uninstalling If your version has the option from the Help menu select Backup/Restore then create a backup on an external device this will copy all your main settings (Not your actual music files) ready to restore on your new computer.