Hi Viswa ,
SFDC sandbox refresh is a usual activity to synchronize SFDC production data to Sandbox ( for user testing and other business validations)
whenever refresh happens all the SFDC user password get reset ( there are options to avoid password reset after reset , you need to discuss with SFDC admin and change the integration user settings in SFDC) which would result in connection errors in SAP PI layer
please make sure that you validate the below steps
1 ) contact to the SFDC admin\support team and validate that the SAP PI user credentials are same as before. If you are connecting using SOAP adaptor ( not using SFDC third party adaptor) you need to also validate the security token Id is not changed. We connect to SFDC using the combination of password + Security token
2) Validate the user credentials by calling SFDC Login API. Login URL might change based on the SFDC server. ( you can use SOAP API or any other third party tool to test this)
https://cs24.salesforce.com/services/Soap/c/30.0/....
3) Validate you get a success response from SalesForce with a dynamic session Id and server URL
4) if you made a successful attempt , you are good to test from PI. If not , contact the SFDC team again and validate the user credentials
