Welcome to Nestwell Property Managements 24/7 DIY Maintenance Center. Thank you for your question about your running toilet.
Generally, when a toilet runs it's caused by too short of a chain on the flapper, or by a flapper that needs to be replaced. There is a separate article detailing how to adjust a flapper chain. The following video will show you how to replace a flapper:
If you need additional assistance, please log in to your Resident Portal and Request a Repair.
Please be aware, if a vendor is required to attend the issue, and the replacement of the flapper is the resolution to the issue, trip fees, and other associated fees will be applied to your tenant ledger in the month following the vendor's visit.