Is there a standard method to validate whether a bigWig file is correct? I have a bigWig file of extension *.bw (which is standard), but I am suspicious that this file may be of an incorrect format. 

Is there a standard method in the field to validate a *.bigWig file?
There's no standard validation method, but a simple one would be python -c "import pyBigWig; bw = pyBigWig.open('your_file.bw'); print(bw.IsBigWig());". If you get True then it's a bigWig file. If you get False or an error then it's not (False indicates a bigBed file).

Alternatively, file your_file.bw should return data.