Bypass the alarm

If you have the key you should be fine. Check your owner's manual for how to shut the alarm off once you're in the car with the key in the ignition if it does't shut itself off. Again, once you're in and have it running you can simply pull the relay under the hood to make the horn and lights stop. You will also have no horn though, and the security system will still be functioning, it just won't be making a bunch of noise. If it actually won't start with the key, or if you don't have the key or if it is perhaps not your vehicle you will need to have it towed to a dealership for them to sort out.

Ive tried disconnecting the battery cable for a whole day even but as soon as i plugg it in my theft alarm comes back on really loud and it wont shut off, i dont know which fuse turns alarm off cause ive tried the horn fuse but thats not it,

If the fuse to the horn is removed its impossible for the horn to sound. Check again. You're probably pulling the wrong fuse. It won't fix your alarm problem but at least it will keep the car quiet until you can find the problem.