Hi Sudha,
As Mallinath said, there are standard reports available in SAP. You can search in SCN before posting, hope you will get it.
1. ME2L for Purchase Orders by Vendor
2. ME2M for Purchase Orders by Material
3. ME2N for Purchase Orders by PO Number
4. MKVZ for Total vendor's list
5. MB5S for purchase orders where GR & IR quantities do not balance. You can view the purchasing organization, purchasing group, Vendor, Purchasing document Number, Item Number,Received quantity, Quantity invoiced.
6. ME80FN for This report can be used for displaying the information of purchase orders created and the transactions that has taken place where you can drill down and summarize data.
Regards
Mani