There are situations where central contract screen doesn't have standard item types available for the selection, this might happen once the service procurement is activated or a custom document type is created for the contract scenario. To restore back all the item types which are required, please follow the below steps.
1) First activate the service procurement if not done earlier.
SPRO >SRM Server >Cross application basic settings >sevice
procurement >Activate service procurement innovations
2) Go to SM34 - View cluser maintenance and enter /SAPPSRM/VC_HT
3) Press Maintain and select Assign to Transaction type and Maintain the Trans type with the Hierarchy template.
Trans type Hierarchy Template
4) Press save
5) Log into SRM and check the central contract page, system should show all the item types.