I tried to go system settings>keyboard>shortcuts but not working. Whenever I click 'left shift', it automatically shows desktop.. How can I fix this?
Depends on which version of macOS you’re using right now.
For Ventura, see this steps in order to return the shortcut to its default
On your Mac, choose Apple menu 
> System Settings, click Keyboard 
in the sidebar (you may need to scroll down), then click Keyboard Shortcuts on the right.
In the list on the left, select a category, such as Mission Control or Spotlight.
In the list on the right, select the tickbox next to the shortcut you want to change.
Double-click the current key combination, then press the new key combination you want to use.
You can’t use each type of key (for example, a letter key) more than once in a key combination.
Quit and reopen any apps you’re using for the new keyboard shortcut to take effect.
If you assign a keyboard shortcut that already exists for another command or app, your new shortcut won’t work. Find the menu command that’s using it, then reassign the keyboard shortcut for that item.
If you want to return all the shortcuts to their original keystroke combinations, go to Keyboard settings, click Keyboard Shortcuts, then click Restore Defaults in the lower-left corner.
For Monterey:
On your Mac, choose Apple menu 
> System Preferences, click Keyboard 
, then click Shortcuts.
In the list on the left, select a category, such as Mission Control or Spotlight.
In the list on the right, select the tickbox next to the shortcut you want to change.
Double-click the current key combination, then press the new key combination you want to use.
You can’t use each type of key (for example, a letter key) more than once in a key combination.
Quit and reopen any apps you’re using for the new keyboard shortcut to take effect.
If you assign a keyboard shortcut that already exists for another command or app, your new shortcut won’t work. Find the menu command that’s using it, then reassign the keyboard shortcut for that item.
If you want to return all the shortcuts to their original keystroke combinations, go to the Shortcuts pane of Keyboard preferences and click Restore Defaults.
Depends on which version of macOS you’re using right now.
For Ventura, see this steps in order to return the shortcut to its default
On your Mac, choose Apple menu > System Settings, click Keyboard in the sidebar (you may need to scroll down), then click Keyboard Shortcuts on the right.
In the list on the left, select a category, such as Mission Control or Spotlight.
In the list on the right, select the tickbox next to the shortcut you want to change.
Double-click the current key combination, then press the new key combination you want to use.
You can’t use each type of key (for example, a letter key) more than once in a key combination.
Quit and reopen any apps you’re using for the new keyboard shortcut to take effect.
If you assign a keyboard shortcut that already exists for another command or app, your new shortcut won’t work. Find the menu command that’s using it, then reassign the keyboard shortcut for that item.
If you want to return all the shortcuts to their original keystroke combinations, go to Keyboard settings, click Keyboard Shortcuts, then click Restore Defaults in the lower-left corner.
For Monterey:
On your Mac, choose Apple menu > System Preferences, click Keyboard , then click Shortcuts.
In the list on the left, select a category, such as Mission Control or Spotlight.
In the list on the right, select the tickbox next to the shortcut you want to change.
Double-click the current key combination, then press the new key combination you want to use.
You can’t use each type of key (for example, a letter key) more than once in a key combination.
Quit and reopen any apps you’re using for the new keyboard shortcut to take effect.
If you assign a keyboard shortcut that already exists for another command or app, your new shortcut won’t work. Find the menu command that’s using it, then reassign the keyboard shortcut for that item.
If you want to return all the shortcuts to their original keystroke combinations, go to the Shortcuts pane of Keyboard preferences and click Restore Defaults.
I changed left shift key to "go to desktop" shortcut. But wanted it back to original shift key function.
