Hi HasnainAfxal,
As I’m sure you’ve read here on GMAT Club, MANY students suffer from nerves and anxiety when taking the GMAT. To help manage your nerves, you could try some visualization techniques. Imagine various test-day scenarios such as getting stuck on a question, issues in the testing center, feeling pressed for time, or worrying that you’re underperforming. As you feel your stress responses start to kick in when thinking about these things, practice pulling yourself together and visualize focusing on getting correct answers.
When taking the GMAT, the best way to deal with stress is to get busy answering the question in front of you, focusing completely on the task at hand so that you redirect all of that nervous energy and naturally calm down. In other words, you distract yourself with a goal. Just tell yourself that all that matters is getting the correct answer to the question in front of you, and then when you have finished that question, take the same attitude toward the next one. Focus on winning each “mini-battle” and you won't have time for anxiety. If you can win enough of those battles, you can win the GMAT war, right?
You also have to consider that your issue is related to an overall lack of verbal knowledge. After all, if you knew GMAT verbal like the back of your hand, you would have supreme confidence when answering questions and thus be able to keep your nerves at bay, right? So, although you do not have much time until your GMAT, you really need to ensure that you have a solid grasp of the foundations of GMAT verbal. To improve your verbal skills, you need to follow a linear study plan that allows you to start with the foundations and move to more advanced topics, thereby allowing you to methodically fill in gaps in your knowledge and improve your skills.