Sorry, but this is one of those "how long is a string?" questions. There are too many variables and not enough info to give a dependable answer.
Oxygen is not a friend of wine. Wine doesn't like bright light very much either. Recork it and put it in a cool (50-55° F), dark place. 60+% humidity is ideal, too dry and the cork will dry out, shrink and let oxygen in.
Here's the fun part – It's up to you when it's bad. What may be undrinkable to you may be just the way I like it. When wine goes bad it loses it's flavor and aroma, eventually it will turn to vinegar.
Open the bottle and take a sniff. If it smells OK, then take a little sip. If it tastes OK, then use it or drink it. DO NOT cook with a wine you wouldn't drink. If I'm going to cook with wine I always have a small glass while I'm cooking (quality control).
One bottle of opened wine could last weeks or months before you find it undrinkable. While another bottle of the same wine is undrinkable as soon as you open it. Wineries lose 1-2% of bottled wine because of bad corks. I've bought wine from the winery and it was bad 4 hours later when we opened it for dinner. I've also forgotten wine for months after I opened it, it was still very drinkable.
There are all kinds of gadgets to help recork wine, but I know none of the brethren like gadgets so I won't go into them here.
Stored properly some reds will improve with age, but most are RTD (ready to drink) when you buy them. Whites and roses are RTD and rarely improve with age.
Putting it in the fridge will slow the process, but could cause deposits to develop in the wine over time.
Bottom line – There are few things that can happen to a wine that will be dangerous to you, but many that might make it unpleasant. It's up to you to decide.