How to fix “QuickBooks won’t open your company file” issue:
Carry out the below-given steps to rectify any of the above-given error messages.

First of all,  ensure that the problem is with the file & nothing wrong is the in the program.  Click the ‘Control key’ & double click the QuickBooks Icon. In case QuickBooks does start, then it is a problem. However, if you know that this is not the problem then perform the below steps.

Ensure you are working on the latest version of QuickBooks.
Now open the file on the same version that was last opened.
Perform the following tasks:
Go to Windows, look for the company file on your device.
Now right click the file to select ‘Properties.’
Go to ‘Properties’ and select QuickBooks
You will view a box that will show a previously used version.
Open the ‘company file via QuickBooks.’ To do this carry out the below steps.
Navigate to the ‘File menu’ and select ‘Open/Restore company.’
Now select the appropriate ‘radio button’ depending upon the file type.
Now go to the location where the ‘Company file’ is located & select the file.
Do the steps to put the file in the ‘Correct location.’ For the Accountant’s copy, you need to go to ‘File menu’ and choose ‘Convert Accountants copy transfer file.’
Now stop all the reports and the QuickBooks Windows to open. You can do this by pressing the ‘Alt Key.’
Choose the file & press Alt key
Select ‘Open’ and come to a login window. You need to release the ‘Alt key’ & give the login info.
Click the ‘Alt Key’ again when you press OK.
Now hold the ‘Alt key’ until the file opens up or see an error message.
Try to open and view ‘a sample company file. If you fail to open one, then it means there is a QuickBooks Installation issue.
Now change the ‘Company file location.’
View the properties of this file. Navigate to Window Explorer & right click on the ‘File’ to select properties. The file size needs to be minimum of 7 MB & it shouldn’t be encrypted/compressed.
Now try ‘renaming the file.’
Remove the multi-user access by ‘clicking’ on ‘Utilities’ option in the file menu.