Can't log into office 365 account from new laptop

I have a new Dell laptop, and can't log into my office 365 account.  I can log in from other devices.  I get an error message saying that my username or password may be incorrect, but these work on other devices.  I can't see any option to eg set a new password, and it may be that I've entered a wrong password too many times from the new laptop.  Any ideas gratefully received!