Hi @ramzyatallah,
It looks like you have a Caesarstone benchtop, which has cracked the whole way through.
Unfortunately, the only great solution would be to widen the gap, apply a specialised adhesive to secure the parts to each other, then apply a filler product over the top to conceal the crack.
Due to the complexity and risks from grinding that would be necessary to carry out this repair, I would suggest you contact Caesarstone to get a quote from a professional repairperson.
If you are just looking to cover the gap, you could try using PC-11 56g White Epoxy Paste, but it is likely that it would stand out and it may crack due to movement quite quickly.
Let me know what you think and if you have further questions, please don't hesitate to ask.
Jacob
