Q:

cannot view azure pipelines

In my current company a previous developer left who setup within Azure devOps a pipeline connecting to GitHub which builds and releases an API (service).
I cannot view any builds, logs,  pipelines etc. I am assuming this is because he has deleted it?
I have owner credentials on azure.
Does this mean  he has deleted the pipeline? Is there away to be able to restore the previous work.

A:

There is no way to restore deleted pipelines and builds using UI.
BUT, there's a way to do so using scripts.

the script will only work if the definitions were deleted less than 4 week ago
You need to create a personal access token (PAT) in the account you use for azure DevOps
there's no need to encode the $accountName, $projectName and $definitionNameToRecover variables. Values containing spaces will work.
the release will recover the definition od release but not it's history.

you can find the script here. ----> https://docs.microsoft.com/en-us/archive/blogs/aseemb/how-to-undelete-a-deleted-release-definition

