Unable to change gears

[Bike Student In Training]

Hi there guys... Just picked a bike up from my Grandad...

At first I was only able to turn the pedals a couple of times and then it'd completely stick and when released the pedals would spin backwards as though there was too much tension.

I fixed this by loosening the bolt on the crank and the pedals turn fine-ish

Now when I' pedaling its like the chain is popping of the chainwheel and the pedals are spitting my feet off and jolting every other pedal...

^Thats the first problem^

The second problem is that the gears wont change...

The back set of cogs has the chain on the lowest cog (furthest away from the bike) and wont change up through the gears. The front set of cogs has the chain on the lowest gear (closest to the bike)


I can click through the gears on the twist grips, but the chain does absolutely[/color] nothing