Im using a lenovo tablet, and i had originally set my sd card as internal storage, i have ejected the card...
...and that was your second mistake right there.
First mistake was setting it as internal storage to begin with. While totally possible and allowed, it comes with caveats - foremost being you should never remove it. At least not without preparation which you did not do.
Setting as "internal" or "adoptable" (the official term), sets up that SD card as an extension of internal memory. The system sees the internal ram and the SD card as one big pool of memory. Apps, system files, all kinds of stuff can just run across both areas.
By removing part of what is now "internal" memory, the system just lost some portion of what it expects to see. Now it's unstable and probably lost some of the apps it stored there.
The system has tried to recover itself after losing that, and now separated itself from the lost data.
Maybe... just maybe, you can re-insert that SD card, reboot the phone, and it might find everything again. But it's not likely.
The PC can't see anything on the card because when the tablet formatted it for internal storage, it's in a file system format specific to the Android OS system. A PC doesn't know what to do with that.
Internal/adoptable storage is a valid option for low end devices with low ram - 8, 16, maybe even 32 GB - where app storage is tight. But from 32 GB (if extra apps are kept to a minimum) and above really don't need it. Setting the SD card to external or portable storage is better as its also considered "removable" and is formatted to a file system that a PC can see. Then you just save documents, photos, and media like music to the card. And if you remove it, it doesn't mess up the system.
Depending on how bad your device is messed up now, you might have to factory reset, but that's a last resort. You're not getting anything off the card now.