Tenant not responding

[Konrad Wallerstein]

I have a condo I rent out in north Florida.  The tenant has paid the rent regularly for 18 months (and before lived in a smaller condo in the same building for 3 years, always paying the rent on time).  Now she does not respond to emails, there is only voice mail on the telephone and no-one answers the door.  The rent is late - she has paid neither December nor January.  I am currently overseas and have no property manager although I have a very good maintenance team.   

Do I need to write to her giving notice before starting the eviction process?

Can I have the lock drilled and replaced and leave a key with the building manager for the tenant?  I am concerned that there has been a mishap and would like my maintenance man enter and make sure.  Or would this be construed as a lock-out?  Can the maintenance man enter using a current key as long as I send an email to the tenant giving notice he will enter and he knocks before entering?

Man thanks for any and all responses