If you want to get back the deck you had when you first moved into your house, you still can. All it takes is a little know-how and elbow grease to get the job done.
Step 1 - Prep Work
Before you begin the process of resurfacing your wood deck, you will need to power wash it and repair any loose nails.
After clearing all the items off of your deck, wash the surface and allow it to dry for a day or two. Make sure you don't have people around when you power wash to protect against injury. Also, take care not to keep the tip of your power washer too close to the deck surface while washing or you risk permanently damaging the wood. After, use your hammer to pound in any nails that have worked their way up out of the wood. If any nails are loose, pull them out and drive a 3-inch decking screw half an inch away from the hole.
If you wish to reuse a hole for a screw but the hole is now too big, you can drop a tiny sliver of metal, or either a paper or a wooden matchstick in the hole and run the screw, down alongside the shim. If it is metal to metal, use a tiny metal tang with the top bent over so it catches the top of the hole and stays in place while the new screw is inserted.
Step 2 - Patch Work
Mix the epoxy according to manufacturer instructions and apply it to all cracks in the wood. Be sure to use the knife to scrape off as much excess as you can because the wood filler will not sand off easily.
Any board that is too far gone to patch up you can pry off with a pry bar and flip over. The back is likely to be in better condition but it may need cleaning. If you find that the board is rotting, you'll need to buy a replacement before it becomes hazardous to walk on.
Step 3 - Sand
There should not be any finish left anywhere on your deck. Use an orbital sander with 80-grit sandpaper to remove splinters and raised edges, creating a smooth surface. When you're sanding, wear proper protective gear such as gloves, a respirator, and safety goggles to prevent accidents like inhaling dust or having dust fly into your eyes. Next, vacuum the dust or use the leaf blower (if your neighbors don't mind). Sand your deck again using the 100-grit sandpaper this time and then remove the new dust.
Step 4 - Finish
Paint your deck with a protective finish like decking varnish. Wear work clothes you don't mind getting stained, specifically long sleeves and pants to protect your skin from sunburn and the chemicals in the wood finish. When you paint your finish, keep gloves on at all times.
When choosing a protective finish, look for one that will best suit your needs. If your deck gets a lot of sunshine, your wood will last longer if you paint it with a semi-transparent protective finish. However, if you use a clear finish your deck will be better protected against rain.