To install or reinstall Windows 7, you need the ISO Image and the best thing to do is to download them from their source (aka Microsoft) instead of strange torrents that could contain viruses..
Windows 7 Professional x64 (64-bit)
English: http://msft-dnl.digitalrivercontent.net/msvista/pub/X15-65805/X15-65805.iso
German: http://msft-dnl.digitalrivercontent.net/msvista/pub/X15-65813/X15-65813.iso
French: http://msft-dnl.digitalrivercontent.net/msvista/pub/X15-65811/X15-65811.iso
Spanish: http://msft-dnl.digitalrivercontent.net/msvista/pub/X15-65843/X15-65843.iso
Windows 7 Professional x86 (32-bit)
English : http://msft-dnl.digitalrivercontent.net/msvista/pub/X15-65804/X15-65804.iso
German: http://msft-dnl.digitalrivercontent.net/msvista/pub/X15-65812/X15-65812.iso
French: http://msft-dnl.digitalrivercontent.net/msvista/pub/X15-65810/X15-65810.iso
Spanish: http://msft-dnl.digitalrivercontent.net/msvista/pub/X15-65842/X15-65842.iso
Windows 7 Home Premium x64 (64-bit)
English: http://msft-dnl.digitalrivercontent.net/msvista/pub/X15-65733/X15-65733.iso
German: http://msft-dnl.digitalrivercontent.net/msvista/pub/X15-65741/X15-65741.iso
French: http://msft-dnl.digitalrivercontent.net/msvista/pub/X15-65739/X15-65739.iso
Spanish: http://msft-dnl.digitalrivercontent.net/msvista/pub/X15-65771/X15-65771.iso
Windows 7 Home Premium x86 (32-bit)
English: http://msft-dnl.digitalrivercontent.net/msvista/pub/X15-65732/X15-65732.iso
German: http://msft-dnl.digitalrivercontent.net/msvista/pub/X15-65740/X15-65740.iso
French: http://msft-dnl.digitalrivercontent.net/msvista/pub/X15-65738/X15-65738.iso
Spanish: http://msft-dnl.digitalrivercontent.net/msvista/pub/X15-65770/X15-65770.iso
Each ISO contains each version of Windows 7 (Starter etc) so you can switch from one version to another with the right licence key / serial number.