If you are having to Restart your pc(?), (Mac ?), EVERYTIME you attempt to access you WiFi Signal, I would start with the typical course of action, though you haven't provided near enough information about your product or your exact problem.
First of all, make CERTAIN all of your devices are updated to the latest available versions!!!
If not, backup and update away.
Second, open System Preferences/Network/. Then, make certain the top center pull down menu lists the correct "Location:i.e. Apple, next, in the large column on the left, make certain "Wi-Fi" is at the top of the list. If it is missing, look to the bottom of the column and click the "Plus" marker, find your proper "Wi-Fi" listing and "Add" to list. If it doesn't sit at the top, simply "click and drag" to the top. Now, to the right of that column there is another pull down menu call Network Name, make certain that it lists YOUR NETWORK and not your neighbor's or an old, unused Network. If it doesn't, move your curser down to the "Advanced" Tab, Click it, you should see a list of all of the Networks in use in your near neighbourhood. For instance, before I cleaned up and deleted a bunch, my AirPort Extreme Wireless Router picked up about 8-10 Networks from neighboring houses and old Network Names I had used and not Deleted. Make Certain that YOUR "Network Name" is listed and "click/hold" to "drag" to the top of the list. Lower right tab "Apply" should now be available. Click it. You will be one 'page' back, and you should now see YOUR NETWORK in the dropdown list, "Network Name". Assuming you are the administrator and therefore hold the password to allow downloads, unlock locked functions, etc., if you are certain you hold the password, thought it's not vital, I would click the "Padlock" shut at the low left of the screen to prevent changes being made that you don't want.
You should be able to connect to your WiFi now. If not, I would first try a simple, click the "", scroll down to "restart" and "click". In still no WiFi, do another wireless router and modem reset and you should be all set.
If you have done all of this or you do it and it doesn't help, I can't help without more info to trouble shoot. Such as, are you Broadband, what type(Brand, Hz, speed(b,n,g, etc.)) your router is. How old is your router. Is this a new problem, if so, did it start after installing an update or some new app.
Then, there are the settings on the devices you are trying to connect to WiFi. That's a different ball of wax alltogether.
Third, I just had problems with my devices not wanting to stay connected to WiFi, or not connect at all, I would go through the above and get results for a few weeks at first, then days, then hours. Finally, I talked to a local shop that is an authorized Apple Retailer/Repair Center who recommended a new router. I bought the new, v.2 AirPort Express for $99.99, hooked it up, was amazed at the size(it is the size of the new Apple TV box) then, I was amazed at the ease of setup and how it has worked nonstop since that day. Not one restart, no slowdowns with a printer plugged into the USB slot and 2-3 iPhones, an iPod Touch or two and a Macbook accessing it constantly the minute my kids get home from school, Not to mention the Playstation, for online gaming with no more lag, like with our old router. Along with all of my other Apple products, it is easily one of the best purchases I have ever made!!!