To resolve minor issues like slow app loading, random notifications, and unresponsive touchscreen, try restarting your iPhone first. Press and hold the Sleep/Wake button until the 'Slide to Power Off' option appears, then slide it to power off. Hold the Sleep/Wake button down for 10 seconds to force quit the device. If your iPhone is frozen or unresponsive, you can also try pressing and holding the Volume Down button while powering it back on.
This simple reboot process can often resolve issues without requiring any additional steps. However, if the problem persists after a restart, you may need to investigate further or seek assistance from an Apple Support representative.