Computer won't boot up need help ASAP

Without a motherboard manual system and specs their is always a degree of guessing.
I do believe that most system will boot with one stick of ram as long as the ram meets the Windows 7 minimum specs. One just has to figure out which ram slot.
Once booted we can work on what channel the motherboard likes. It's either going to be two black or two yellow which should put that old board in dual channel.

Example:
On the motherboard in my specs I can install just one stick of ram in in slot D-1 which is two slots to the right of the cpu.

Yep mate I think your idea of one stick is a good lateral thought actually as it would only provide one channel anyway eh?

Ok Laith mate on the board there will be a model number / name see pic for typicalplace to find it and you may need a very bright light to see it

The ram does not look like it is installed properly, when pushed fully home the end clips will move inwards and sit level with the clips on the empty slots (which are fully in)
Looks to me that the ram is merely resting in the slots

When in the yellow slots the clips are out then when you show it in the black slots the clips are out and not fully engaged in the groove on the ram stick as circled below

Have a look at this picture, the rear is fully inserted and the tabs are fully engaged compared to the front stick which is obviously not in place yet

After making sure the ram is the right way around (bottom dent is in line with motherboard notch) its usually just a case of giving it a firm push down

I generally insert it squarely so both ends go it at the same time, did you ensure the ram was the correct way around ? if the bottom notch is out only one end will locate and ram stick will seesaw on the motherboard notch under the ram stick