left apartment early but no written contract

I spent a summer in Greece and rented an apartment for my time there. No contract was ever written or signed by me or the landlord, yet we had a verbal agreement of the rent amount and length of my stay. I left early due to unforseen circumstances at home and was unable to notify the landlord or pay the remaining rent.

I have now received a letter explaining the landlord's intention to take further legal action to settle the unpaid rent, as well as her intention to bill me for the legal costs accrued.

Since we had no written agreement, does she have any chance? When I had paid the rent for the months I was living there, there was never any receipts signed by me or documents written by the landlord stating the remaining balance.
Am I under any obligation to pay the remaining rent since there is no record of what is owed?

The landlord will have a very hard time suing or enforcing that, especially with you out of the contry.

Pay what you think is fair given what you said to the landlord, but any court action is very unlikely.

Again, the above poster is incorrect. Without a written agreement, a month to month tenancy was established. (See previous post as to why) There is a requirement in most countries and states to give a required amount of notice prior to vacating unless you have an established term lease and you vacate at the end of the term. You are responsible to give this amount of notice and pay the rent for this period as well as any other obligations under the agreement. Look up the required notice to terminate an at-will tenancy in the area you rented (these notices vary in length as per area, not country) and pay the rent for that period of notice.

Since the lease was never signed to establish a term for the tenancy, he can not hold you liable for rent beyond the required notice period. He can bill you for the rent and any legal costs for recovering it (if a judge allows him those costs in the claims suit against you). You would have to appear in court there to defend yourself against his claims of monies owed. If you failed to appear, most courts rule in favor of the party present. That judgement can be given to a collection agancy or sold to an agency to continue to contact you for collections. Pay for the required notice period and be done with it. You should have at least send him a written notice when you had to vacate suddenly.