Is it true that ozone layer on the earth will be fully disappeard after 7or8 years?

No that is not true. Do some more research and you will find that the uproar over the hole in the ozone is mostly over, as the "hole" apparently is closing. Some attribute this to the reduction in fluorocarbon production, no more freon in air conditioners.,, and use and others attribute it to natural activities and cycles. But evidence shows the Ozone is safe