There is approximately 10000 tutorials on how to use structs in save games on YT. Pick one, study it, get your mind around the concept, apply it to your case. No one can do this for you, sadly.
If you have an issue with something very specific, do provide the details of what is not working.
All I meant is that no one is capable of helping with the details of the implementation without knowing how the system works. Each inventory is unique in that sense. However, the very same general principles apply to all of it.
Launch a new project:
create a struct with data
save that struct
load it
do the same with array
Can you get that part going? If so, apply it your project, bit by bit:
can you save just the name of the inventory item?
can you say an array of items names?
can you load them
…
and so on
Break it into small manageable bits and work on that.