This is an interesting and unusual scenario.
1. You have a system partition (E) and judging by the amount of data it contains it seems to contain a bootmgr (probably that of Windows 7). But that partition is not 'active' and thus this bootmgr cannot function.
2. On the other hand you have an active C partition which seems to contain the Windows8 bootmgr (I assume that because I assume that your Windows8 does boot).
As a first test I would deactivate the C partition and activate the E partition. For that you need to download the bootable CD of Partition Wizard
(last entry on the webpage). Burn that to CD and load from the CD. Highlight the partition you want to manipulate and the controls are in the Partition tab > Modify.
If my theory is right, your Windows7 should now boot - but most likely Win8 will no more boot. If that is the case, we'll see what we can do about that.