suppose in a frequency table a value is 0 eg. there are no cycles that have been sold in 4th week (example only) so what should we write in tally marks frequency ? (in the table )

We will not show anything under the tally marks column, if there is no observation corresponding to that class interval.
Consider the following example.

The following marks (out of 50) obtained in Science by 30 students of class 8 are :
9, 25, 19, 18, 17, 41, 42, 20, 4, 15, 50, 44, 49, 6, 12
27, 29, 40, 43, 5, 19, 22, 46, 50, 21, 11, 7, 41, 20, 25

Now, we will draw a frequency distribution table using tally marks for the following data.
 

MARKS (class intervals)	Tally marks	Frequency (No. of students)
0-10	$\bcancel{\left|\right|\left|\right|}$	5
10-20	$\bcancel{\left|\right|\left|\right|} \left|\right|$	7
20-30	$\bcancel{\left|\right|\left|\right|} \left|\right||$	8
30-40		0
40-50	$\bcancel{\left|\right|\left|\right|} \left|\right||$	8
50-60	$\left|\right|$	2
	Total	30

Hope this would have clear your doubt.