After scratching my head for few days, I was finally able to fix an error that was preventing me from accessing my vCenter Serve GUI.
So, I checked also on the vCenter Server Management and found that the VMware vCenter server has stopped.I tried to restart it and failed to do so.
The system was throwing out some error and referred me to check the syslog, which turned to contain no trace of the error Then I realized that there was a time synchronization issue between the vCenter and the ESXi host.
A little trick helped fix the issue.I just disabled and reenabled the Time Synchronization and restarted the process and didn't the error message, and it worked.Give it a try and let me know if that helped your case