I am a senior financial manager and working smartly in a financial company

I am a senior financial manager and working smartly in a financial company. The company has assigned me a big database of financial entries. Hence, I am using QuickBooks for managing the accounting entries in the proper ways. When I attempt to open company file, I am experiencing QuickBooks won’t open company file. This error is making me more annoying, hence I am not able to work on my software. I have taken the suggestion from certified QuickBooks advisors. Can anyone provide the simple ways to resolve QuickBooks won’t open company file?