I have lost my micro sd card and am unable to use my raspberry pi 3B. I can't buy a new one since online delivery has been stopped where I live due to the lockdown. Is it possible to boot my raspberry pi using a USB pen drive or another sd card(That one is big, it is not a micro sd card and it is just 2 gb). I also have a micro-sd card reader in case that is required. Thanks in advance.
Your Question is unclear - do you have a Pi3B or a Pi3b+?
The Pi3b+ can be booted from USB.
The Pi3b can be booted from USB only after it is enabled (which requires SD Card).