Excel error

Are you able to provided the exact coding and spreadsheet, so that we can try and reproduce it?

Have you tried repairing your installation of Office/Excel?

Also ensure you have sufficient access to files and folders, as this can cause an impact too. I don't know where you are reading your Excel file from.

In your original project, read the Excel file from C:\Temp, and see if it works.

You will have to get your computer looked at by your IT, as I'm unable to suggest anything else.

You say that the scripts work fine on another machine, accept for yours .Which usually indicates there's some sort of issue with your machine, which could be relating to Office/Excel.

What do you mean by I am fetching those excel files from user profile "environment variable"?

Your files should be in %userprofile%\Documents and not in %userprofile%. You may have access to that folder when using Explorer, but it doesn't necessary mean that TestComplete will have the appropriate permissions to access it.

I suggest you create a folder C:\Temp, copy your Excel in that folder, and then try to run your script using that path to see if it works.

Your function doesn't looks correct

I see the code like this,

function environmentVar()
{
    envVar = aqEnvironmentVariable.GetEnvironmentVariable("USERPROFILE");
    envVarfolder = envVar + "\\DMData\\";
    if (!aqFileSystem.Exists(envVarfolder))
        aqFileSystem.CreateFolder(envVarfolder);
    else
        Log.Message("Folder Exists");

    if (!aqFileSystem.Exists(envVarfolder + "\\DMMobile")) 
    {
        Log.Error("Excel file doesn't exists");
        Runner.Stop();
    }
}

function getExcelData(filename)
{
    var excelFile = Excel.Open(envVarfolder + "\\DMMobile.xlsx");
    var excelSheet = excelFile.SheetByTitle(fileName);
    return excelSheet;
}

You create a folder called DMData in %userprofile%, if it does not exist. You then check if the folder DMMobile does not exist, and output "Excel file doesn't exists" - are you checking the folder or file?

Then you get the Excel file DDMobile.xlsx from folder %userprofile%\DMData - which will not exist, if you've created the folder.

I don't really understand what's going on. Why can't you just read the Excel file as normal!?

Should you not be then checking for the filename that has .xlsx e.g.

 if (!aqFileSystem.Exists(envVarfolder + "\\DMMobile.xlsx")) 

 as opposed the folder name

 if (!aqFileSystem.Exists(envVarfolder + "\\DMMobile")) 

?