You don't seem to have anything for sale.
Are these non-eBay transactions? You'll have to reply through the appropriate website or through Paypal.
Did you receive the offers as emails? Can you click Reply on the email?
Note that while the buyer is safer to buy through eBay with Paypal, PP does offer pretty good buyer and seller protections when a private sale is being paid through them.
Oddly, many scammers have not figured this out.