Black Candles are bearish lines in candlestick and candlevolume charts. They signify that the closing is lower than opening for that time period.
CHKDSK, short for Check Disk, is a utility that checks the integrity of the files and file structure of your hard disk. I'll walk you through it. I have disk problems and you said I should run CHKDSK. Great.
To get to Disk Cleanup... Open File Explorer or My Computer. Right click the (C:) drive, and select Properties. The Disk Cleanup button is in the first tab that opens. This works in Windows XP and probably earlier, as well as on Windows 7, 8, and 8.1 - probably in Win 10 but I haven't tried that yet.