Bonnet release cable is broken - how do I open the bonnet. A photo of where the catches are would help

You will need to reach up from underneath and either locate the latch and pull it or grip the cable near the latch and pull that to try and release the bonnet catch!

cable is undone or broken

The cable can break either at the left or right hand latch - if you are lucky as I was, the cable operating the left hand catch was the broken one, and was broken near the right hand latch release mechanism.
I was able to open the right hand latch with the bonnet release from inside thecar.
You then have to get a piece of fairly strong wire(I used a 2.8mm welding rod) and bend a fairly tight hook in one end. Using a torch so you can see the bonnet release cable, feed the wire in through the grill and hook the swage on the end of the cable that operated the left hand latch. A frim pull on the wire should then release the left hand latch.
Good luck!

if the bonnets cable is not broken wiggle one corner of the bonnet and see if it will release the catch. You may have to push on the corner very hard rapidly even on both sides if one side does nbot work for you. I find that to work on most cars. The problem for most cars that the hood or bonnet adjusters are worn and bind the opening process

You don't specify whether its just that you can't find the release catch, or whether the release catch is stuck / broken,

In the UK (Right hand drive car) the release catch is situated in the left (passenger side) footwell, within about a foot of the lower front door hinge. In a Left Hand Drive car, I guess this would be reversed (i.e. right hand side footwell). Pull, and it semi releases the hood. Next, walk to the front of the car, pull the hood up about 1" and insert your fingers about a foot left of center. Sweep to the right, and you'll release the secondary catch and the hood will be open.

However, if its stuck / broken, then ......

You need to work underneath the front of the vehicle - the idea is to get at the catch and release it with a long screwdriver flicking the catch to open the bonnet -or getting a grip of the cable if it is hanging loose ( i.e. broken ) then getting a grip of the cable with mole grips or even pliers - to pull and release the cable / bonnet.

Once the bonnet is open - you can deal with renewing the cable assembly, or greasing it thoroughly.

REMOVED PANEL FROM UNDER THE BUMPER AND REACHED UP TO THE TOP OF BONNET AND LOCATED CABLE. PULLED ON CABLE WHILST 3RD PARTY PULLED BONNET LEVER IN DRIVERS FOOTWELL. BONNET RELEASED.

Get a second person to pull bonnet catch and you push up and down on the bonnet whilst catch is being pulled. 1, cable possibly stretched, 2, look at bonnet catch under the coloum to see if wire is attached, 3, try and lie under car and look up the back of the bulkhead to see the catch and release it manually. Hope that helps.

first of all not an easy job,you need to get the front grill off and look upwards for a cover that will be covering up the bonnet catch,basicly bend or pull this off,you should then see were the cable goes in,then you should be able to bar the catch with a screwdriver to release it. best of luck

Most of the time the cable snaps at the release handle. If you remove the handle and get the end of the cable, you can cut off the cable jacket and use needle nose pliers or vise grips to grab the cable and pull to release bonnet.

There are two release catches about 15" to the right and left of the centre safety catch. Roughly at each end of the top of the radiator.

The bonnet release cable goes first to the right hand one then there is a wire from that to the left, in a daisy chain way. They are typically French, cables fit into plastic levers ( a bit like bike brakes) not metal which break easily. replacements are not cheap. You need to be able to pull the cable to both catches to get the bonnet up. I managed to do this from underneath. In my case the, left hand one was broken and right hand one was working, but the getting it open broke the bit that that pulls the left. Managed to away with buying just one new catch as they are identical, swopping the right partly broken one over to the left side.

HTHs