I assume that when you say I want to get top 5 item you are referring to the top 5 by 'Item', because you then go on to talk about getting the Price and the Product for them.
1. If Item is repeated, as it is in your example (Pen and Eraser both =20), then it is not possible to get the correct price and item.
2. If Item is unique and you have the top 5, Excel's VLOOKUP() function only does the lookup on the first column of a table or range of data and returns values from columns to the right.
3. To use your data for a VLOOKUP(), add a new column to the left of the Product column and create a copy of the item value.
A B C D
1 Item(copy) Product Item Price
2 20 Pen 20 100
3 50 Pencil 50 300
4 20 Eraser 20 200
5 40 Calculator 40 500
Cell A2 has the formula =C2, then drag it down column A alongside the existing data.
=VLOOKUP($D9,$A$2:$D$5,2,FALSE)where D9 contains the Item to be searched for, will now return the Product and
=VLOOKUP($D9,$A$2:$D$5,4,FALSE)will return the Price.