How Can I Access Files on My Hard Drive?

You can find SATA to USB adapters specifically for 3.5-inch drives on Amazon. Make sure it includes an AC adapter to power it from an outlet. An enclosure for a 3.5-inch drive will also do the trick.

There's a small adapter board over the SATA connectors; gently remove that first. After that, you can use any SATA hard drive enclosure to connect it to your computer.

It sounds like your drive might be from a USB enclosure. You will need to disconnect the board from the enclosure and either connect it directly to a desktop using SATA cables or find the right cables for the enclosure. Just be careful with power bricks — they need to match the voltage and polarity, or you could damage the drive. Once connected, the drive should work if it's formatted in NTFS or exFAT, and you'll be able to access your files right away.