How do I sort out QuickBooks won't open company file?

In the middle of urgent business meeting, my QuickBooks won’t open company file. This is often the foremost common error which will be appeared anytime. Thanks to the occurrence of this error code, my important task is on pending. I’m trying to open QuickBooks company file, but I’m not getting the success. There could also be unexpected reasons of this issue. Actually, I’m new this accounting tool, hence I don’t have enough experience for it. So, I’m getting to share this error with all of you, guys. Can anyone provide simple tips to repair this error?