Uninstalled Akarmai Download Mangerer, how do i get it back?

you don't need the akamai downloader, but if you want it it will install when downloading something that uses it.

as for your 7z file, you need to download the matching exe (which will extract the 7z and start your installation when both files are placed in the same directory and the exe is double clicked).

Downloadable installation files available:

• Suites and Programs:  CC 2014 | CC | CS6 | CS5.5 | CS5 | CS4, CS4 Web Standard | CS3
• Acrobat:  XI, X | 9,8 | 9 standard
• Premiere Elements:  13 | 12 | 11, 10 | 9, 8, 7 win | 8 mac | 7 mac
• Photoshop Elements:  13 |12 | 11, 10 | 9,8,7 win | 8 mac | 7 mac
• Lightroom:  5.7.1| 5 | 4 | 3
• Captivate:  8 | 7 | 6 | 5.5, 5 | 1
• Contribute:  CS5 | CS4, CS3 | 3,2
• FrameMaker:  12, 11, 10, 9, 8, 7.2

Download and installation help for Adobe links

Download and installation help for Prodesigntools links are listed on most linked pages.  They are critical; especially steps 1, 2 and 3.  If you click a link that does not have those steps listed, open a second window using the Lightroom 3 link to see those 'Important Instructions'.